Methods and compositions for expressing functional class XIV myosin

ABSTRACT

The invention, in part, includes methods and compounds useful to prepare and functional class XIV myosin. Functional class XIV myosin prepared using methods of the invention may be useful to screen for and identify compounds that inhibit and treat parasitic infections and contamination.

RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/993,752, filed May 15, 2014 the content of which is incorporated by reference herein in its entirety.

GOVERNMENT INTEREST

This invention was made with government support under grant numbers AI054961 and R01 GM078097 awarded by the National Institutes of Health. The Government has certain rights in the invention.

FIELD OF THE INVENTION

The invention, in part, relates to methods to prepare, assess, and utilize functional class XIV myosin.

BACKGROUND OF THE INVENTION

Class XIV myosins play an important role in the life cycle of apicomplexan parasites of medical and/or veterinary importance, such as Plasmodium spp, Toxoplasma gondii, Sarcocystis neurona and Cryptosporidium parvum. One example of an apicomplexan parasite is Toxoplasma gondii, which is a member of the phylum Apicomplexa and is a common infectious agent of humans that can result in health risks to immune-compromised individuals and the developing fetus. This obligate intracellular parasite must penetrate a host cell and replicate to survive. The invasive stage of the parasite relies on a unique form of substrate-based motility called gliding motility, which is driven by a class XIVa myosin motor, TgMyoA that is powered by an actomyosin-based complex, which is called the “glideosome”. The class XIV myosin TgMyoA heavy chain is one of eleven myosin heavy chains found in T. gondii (1) and is an essential component of the glideosome, which is necessary for efficient parasite motility, invasion, and egress from the host. Parasites lacking TgMyoA are avirulent in a mouse model of parasite infection (2).

The TgMyoA motor is located between the plasma membrane and the inner membrane complex (IMC), a double membrane that is continuous around most of the cell (3). TgGAP50 (a 50 kDa gliding associated protein), an integral membrane glycoprotein of the IMC, acts as a membrane receptor for the motor (4); TgMyoA is linked indirectly to TgGAP50 through an apicomplexan-specific N-terminal extension of its regulatory light chain, TgMLC1, and TgGAP45 (a 45 kDa gliding associated protein). Several other proteins, including TgGAP40 (a 40 kDa gliding associated protein), TgGAP70 (a 70 kDa gliding associated protein), and TgELC1 (a putative essential light chain) have recently been identified as additional components of this myosin motor complex (5, 6). The mechanism by which the motor complex generates motility has remained unclear.

SUMMARY OF THE INVENTION

In one aspect of the invention, methods for preparing a functional class XIV myosin are provided. Compositions that include functional class XIV myosin polypeptides and their encoding polynucleotides are also provided in some aspects of the invention. In some aspects of the invention, methods of using functional class XIV myosin are provided and may include, in some aspects, use in screening assays to identify candidate compounds that reduce the level of activity of a class XIV myosin polypeptide.

According to one aspect of the invention, methods of producing a functional class XIV myosin polypeptide are provided. The methods include co-expressing three or more polynucleotides in an expression-system cell, wherein the three or more polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide, a first myosin light chain polypeptide-encoding polynucleotide, and a parasite co-chaperone polypeptide-encoding polynucleotide, wherein the three or more polynucleotides are co-expressed in the cell under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first myosin light chain polypeptide. In some embodiments, the class XIV heavy chain polypeptide-encoding polynucleotide, the parasite co-chaperone polypeptide-encoding polynucleotide, and the first myosin light chain polypeptide-encoding polynucleotide are each independently selected from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium class XIV heavy chain polypeptide-encoding polynucleotide or a functional variant thereof; a parasite co-chaperone polypeptide-encoding polynucleotide or a functional variant thereof; and a myosin light chain polypeptide-encoding polynucleotide or a functional variant thereof, respectively. In certain embodiments, the Toxoplasma is Toxoplasma gondii; Plasmodium is Plasmodium falciparum, P. vivax, P. knowlesi. P. ovale, or P. malariae; Neospora is Neospora caninu or Neospora hughesi; Sarcocystis is Sarcocystis neurona, bovihominis (S. hominis,), or S. suihominis; Eimeria is Eimeria tenella, E. bovis, E. necatrix, E. ellipsoidalis, or E. zuernii; and Cryptosporidium is Cryptosporidium parvum, C. hominis, C. canis, C. felis, C. meleagridis, or C. muris. In some embodiments, co-expressing includes co-infecting the expression-system cell with one or more expression vectors each including one or more of the three or more polynucleotides. In certain embodiments, the one or more expression vectors is a viral expression vector. In some embodiments, co-infecting the expression-system cell includes co-infecting with one or more expression vectors comprising one or more of the class XIV heavy chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, the first myosin light chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, and the parasite co-chaperone polypeptide-encoding polynucleotide operably linked to an independently selected promoter. In some embodiments, co-infecting the expression-system cell includes co-infecting with a first expression vector comprising the class XIV heavy chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, a second expression vector comprising the first myosin light chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, and a third expression vector comprising the parasite co-chaperone polypeptide-encoding polynucleotide operably linked to an independently selected promoter. In some embodiments, the one or more of the expression vectors additionally comprises one or more polynucleotides that encode: a myosin light chain-1 (MLC1) polypeptide or functional variant thereof, a tail domain interacting protein (MTIP) or functional variant thereof, an essential light chain-1, (ELC1) polypeptide or functional variant thereof, an essential like light chain, calmodulin or a functional variant thereof, or a glideosome associated protein-45 (GAP45) or a functional variant thereof. In some embodiments, one or more of the expression vectors additionally comprise at least one polynucleotide sequence that encodes a detectable label. In some embodiments, the detectable label comprises one or more FLAG tags, biotin acceptor sites, Myc tags, His tags, or Ty1 tags. In certain embodiments, the amino acid sequence of the biotin acceptor site comprises the sequence set forth as SEQ ID NO:21 or a functional variant thereof; the amino acid sequence of one or more of the Myc tags comprises the sequence set forth as SEQ ID NO:22 or a functional variant thereof; and the amino acid sequence of the one or more of the Ty1 tags comprises the sequence set forth as SEQ ID NO:23 or a functional variant thereof. In some embodiments, the parasite co-chaperone polypeptide-encoding polynucleotide sequence comprises a UNC-45/Cro1/She4p (UCS) chaperone polynucleotide sequence, or functional variant thereof. In some embodiments, the parasite co-chaperone polypeptide is derived from the sequence of a toxoplasma gondii UCS-45 homolog, a Toxoplasma UNC (TgUNC) polypeptide, or a functional variant thereof. In some embodiments, the TgUNC polypeptide comprises the amino acid sequence set forth as SEQ ID NO:12, or a functional variant thereof. In certain embodiments, the TgUNC polypeptide encoded by the polynucleotide sequence set forth as SEQ ID NO:11, or a functional variant thereof. In some embodiments, the TgUNC polypeptide functional variant is a truncated TgUNC polypeptide. In certain embodiments, the truncated TgUNC polypeptide comprises the amino acid sequence set forth as SEQ ID NO:14. In some embodiments, the truncated TgUNC polypeptide is encoded by the polynucleotide sequence set forth as SEQ ID NO:13. In some embodiments, the parasite co-chaperone is derived from the sequence of a Plasmodium falciparum UCS-45 homolog, a Plasmodium falciparum UNC (PfUNC) polypeptide, or a functional variant thereof. In certain embodiments, the PfUNC parasite co-chaperone polypeptide comprises the amino acid sequence set forth as SEQ ID NO:4, or a functional variant thereof. In some embodiments, the polynucleotide sequence of the PfUNC parasite co-chaperone comprises the sequence set forth as SEQ ID NO:3, or a functional variant thereof. In some embodiments, the PfUNC functional variant is a truncated PfUNC polypeptide. In certain embodiments, the truncated PfUNC polypeptide comprises the amino acid sequence set forth as SEQ ID NO:42, or a functional variant thereof. In some embodiments, the expression system is a baculovirus/insect cell expression system. In some embodiments, the expression-system cell is a Sf9 cell. In certain embodiments, the class XIV myosin heavy chain polypeptide comprises a TgMyoA amino acid sequence set forth as SEQ ID NO:16 or a functional variant thereof. In some embodiments, the class XIV myosin heavy chain TgMyoA amino acid sequence is encoded by the polynucleotide sequence set forth as SEQ ID NO:15, or a functional variant thereof. In certain embodiments, the class XIV myosin heavy chain polypeptide comprises a PfMyoA amino acid sequence set forth as SEQ ID NO:2 or a functional variant thereof. In some embodiments, the class XIV myosin heavy chain PfMyoA amino acid sequence is encoded by the polynucleotide sequence set forth as SEQ ID NO:1, or a functional variant thereof. In some embodiments, the class XIV myosin heavy chain polypeptide is a truncated class XIV myosin heavy chain polypeptide derived from Plasmodium falciparum and comprises the amino acid sequence set forth as SEQ ID NO:24 or a functional variant thereof, or comprises the amino acid sequence set forth as SEQ ID NO:26 or a functional variant thereof. In certain embodiments, the class XIV myosin heavy chain polypeptide is a truncated class XIV myosin heavy chain polypeptide derived from Toxoplasma gondii and comprises the amino acid sequence set forth herein as SEQ ID NO:25 or a functional variant thereof, or comprises the amino acid sequence set forth as SEQ ID NO:27 or a functional variant thereof. In some embodiments, the first myosin light chain polypeptide is a regulatory light chain (MLC1) polypeptide sequence derived from a Toxoplasma gondii regulatory light chain polypeptide sequence, or derived from a Plasmodium falciparum regulatory light chain polypeptide sequence. In some embodiments, the first myosin light chain polypeptide comprises the amino acid sequence forth as SEQ ID NO:18 or a functional variant thereof. In some embodiments, the first myosin light chain polypeptide is encoded by the polynucleotide sequence set forth as SEQ ID NO:17 or a functional variant thereof. In certain embodiments, the first myosin light chain polypeptide comprises the amino acid sequence set forth as SEQ ID NO:6 or a functional variant thereof. In some embodiments, the first myosin light chain polypeptide is encoded by the polynucleotide sequence set forth as SEQ ID NO:5 or a functional variant thereof. In some embodiments, the method also includes isolating the expressed functional class XIV myosin polypeptide. In certain embodiments, the method also includes assaying the function of the expressed functional class XIV myosin polypeptide. In some embodiments, the assay comprises an in vitro motility assay, a binding assay, an ATP co-sedimentation assay, or an ATPase activity assay. In some embodiments, the method also includes additionally co-infecting the expression-system cell with an expression vector comprising a second myosin light chain encoding polynucleotide; and co-expressing the class XIV heavy chain polynucleotide, the first and second myosin light chain polynucleotides, and the parasite co-chaperone polynucleotide under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first and second myosin light chain polypeptides. In certain embodiments, the second myosin light chain polypeptide-encoding polynucleotide encodes a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium myosin light chain polypeptide or a functional variant thereof. In some embodiments, the Toxoplasma is Toxoplasma gondii; Plasmodium is Plasmodium falciparum, P. vivax, P. knowlesi. P. ovale, or P. malariae; Neospora is Neospora caninu or Neospora hughesi; Sarcocystis is Sarcocystis neurona, bovihominis (S. hominis,), or S. suihominis; Eimeria is Eimeria tenella, E. bovis, E. necatrix, E. ellipsoidalis, or E. zuernii; and Cryptosporidium is Cryptosporidium parvum, C. hominis, C. canis, C. felis, C. meleagridis, or C. muris. In some embodiments, the first myosin light chain polypeptide is a regulatory light chain polypeptide and the second myosin light chain polypeptide is an essential light chain polypeptide. In some embodiments, the second myosin light chain is derived from a Toxoplasma gondii myosin light chain sequence or a Plasmodium falciparum myosin light chain sequence. In certain embodiments, the second myosin light chain polypeptide comprises the amino acid sequence set forth as SEQ ID NO:6, 8, 18, or 48, or a functional variant thereof. In some embodiments, the second myosin light chain polypeptide is encoded by the polynucleotide sequence set forth as SEQ ID NO:5, 7, 17, or 47.

According to another aspect of the invention, a functional class XIV myosin polypeptide prepared by the method of any one of the embodiments of the aforementioned claims is provided. In some embodiments, the class XIV myosin polypeptide is an isolated functional class XIV myosin polypeptide.

According to yet another aspect of the invention, methods of determining an activity of a class XIV myosin polypeptide are provided. The methods include (a) preparing a functional class XIV myosin polypeptide as set forth in an embodiment of any of the aforementioned methods; (b) assaying an activity of the prepared functional class XIV myosin polypeptide; and (c) assessing the results of the assay as a determination of activity in the functional class XIV myosin polypeptide. In certain embodiments, the assay comprises an in vitro motility assay, a binding assay, or an ATPase activity assay. In some embodiments, the activity comprises actin movement.

According to yet another aspect of the invention, methods of identifying a candidate compound to inhibit a parasite that expresses a class XIV myosin polypeptide are provided. The methods including (a) preparing a functional class XIV myosin polypeptide as set forth in an embodiment of any of the aforementioned methods; (b) contacting the prepared class XIV myosin polypeptide with a candidate compound under conditions suitable to determine an activity of the class XIV myosin polypeptide; (c) determining the activity of the class XIV myosin polypeptide; and (d) comparing the determined activity with a control activity determination, wherein a decrease in the determined activity in the contacted class XIV myosin polypeptide compared to the control activity determination identifies the compound as a candidate compound to inhibit a parasite that expresses the class XIV myosin polypeptide. In some embodiments, the control activity is activity determined in a functional class XIV myosin polypeptide not contacted with the candidate compound. In certain embodiments, the determining the activity comprises determining at least one of a level of the activity or the presence or absence of the activity. In some embodiments, the candidate compound alters the folding of the class XIV heavy chain polypeptide by the parasite co-chaperone polypeptide. In certain embodiments, the candidate compound alters the interaction between the class XIV heavy chain polypeptide and the first light chain polypeptide. In some embodiments, a means of determining the level of function of the class XIV myosin polypeptide comprises an in vitro motility assay, a binding assay, or an ATPase activity assay.

According to yet another aspect of the invention, methods of producing a class XIV myosin polypeptide are provided. The methods including co-expressing two or more polynucleotides in an expression-system cell, wherein the two polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide and a parasite co-chaperone polypeptide-encoding polynucleotide, wherein the two or more polynucleotides are co-expressed in the cell under conditions suitable to produce a class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide. In some embodiments, the class XIV heavy chain polypeptide-encoding polynucleotide and the a parasite co-chaperone polypeptide-encoding polynucleotide are each independently selected from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium class XIV heavy chain polypeptide or a functional variant thereof; and a from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium parasite co-chaperone polypeptide-encoding polynucleotide or a functional variant thereof. In certain embodiments, the method also includes co-expressing an essential myosin light chain polypeptide-encoding polynucleotide independently selected from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium essential myosin light chain-encoding polynucleotide or a functional variant thereof. In some embodiments, the Toxoplasma is Toxoplasma gondii; Plasmodium is Plasmodium falciparum, P. vivax, P. knowlesi. P. ovale, or P. malariae; Neospora is Neospora caninu or Neospora hughesi; Sarcocystis is Sarcocystis neurona, bovihominis (S. hominis,), or S. suihominis; Eimeria is Eimeria tenella, E. bovis, E. necatrix, E. ellipsoidalis, or E. zuernii; and Cryptosporidium is Cryptosporidium parvum, C. hominis, C. canis, C. felis, C. meleagridis, or C. muris.

This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. The present invention is not intended to be limited to a system or method that must satisfy one or more of any stated objects or features of the invention. The present invention is not limited to the exemplary or primary embodiments described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of ‘including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

Partial Listing of Sequences SEQ ID NO: 1 Plasmodium falciparum 3D7 myosin A (MyoA) mRNA, complete cds, nucleotide sequence: XM_001350111, (also referred to herein as PfMyoA heavy chain) atggctgttacaaatgaagaaataaaaacggcaagtaagattgttagaagagtttcaaatgtagaagcatttga caaaagtggttcagtttttaagggttatcaaatatggactgatatatctccgacaatagaaaatgatccaaata ttatgtttgtaaaatgtgttgtacaacaaggatcaaaaaaagaaaaattaaccgttgtacaaattgatccaccc ggaacaggaactccatacgatattgatccaactcacgcatggaactgcaactctcaagtagaccccatgtcttt tggtgatattggtcttttaaatcacaccaacatcccatgtgttcttgactttttaaagcacagatatttaaaaa atcaaatatacaccactgctgttccccttattgttgcaataaacccatacaaggatttaggaaacacaactaat gaatggattcgtagatatcgtgatacagctgatcatactaagttgccaccacacgtgttcacatgtgctaggga agctttgtctaatctccatggtgtaaacaagagccaaactattattgtatctggtgaatctggtgcaggaaaaa ccgaagcaacaaaacaaatcatgagatattttgcttcttctaagagtggaaatatggatttacgtattcagaca gcaataatggctgcaaatccagttcttgaagcttttggtaatgcgaaaactataagaaataacaattcatctcg ttttggtcgtttcatgcagttggttatatcccatgaaggaggtataagatacggttccgttgttgcttttctgt tggaaaaatctagaattattacacaagatgataatgaaaggtcatatcatatattttatcaatttcttaagggt gcaaatagtacgatgaaatctaaatttggtttaaaaggagttactgaatacaaattattgaacccaaattcaac agaggtaagtggagtagatgatgtaaaagattttgaagaggtaattgaatcgttgaaaaatatggaattaagtg aatcagatattgaagtaatattttcaatagtagctggtatattaacattaggaaatgtaagattaattgagaag caagaagctggattaagtgatgctgctgctattatggatgaggatatgggtgtgtttaataaagcttgtgaatt gatgtatttagaccctgaattaataaaaagggaaatattaattaaggtaactgttgctggaggaacaaaaattg aaggtagatggaataaaaatgatgcagaagtgttgaaatcttccttatgtaaagctatgtatgagaaattgttt ttatggataataagacatttgaattcaagaattgaaccagaaggaggatttaaaacatttatgggtatgttaga tatttttggttttgaagtatttaaaaataattcattggaacaattatttattaacattactaacgaaatgcttc agaaaaattttgtagatattgtttttgaaagagaatcaaaattatataaagacgaaggaatatcaacagctgaa ttaaagtacaccagtaataaggaagtaataaacgtactttgtgagaagggtaaatcagtactttcatacttaga ggaccaatgtttagcacctggaggaaccgatgaaaagtttgtaagttcctgtgctacaaatttaaaggaaaata ataagtttaccccagcaaaagtagcatcgaataaaaattttataatacaacatactataggaccaattcaatat tgtgctgaaagctttttgcttaaaaacaaggatgtcttaagaggtgatttagttgaagtaattaaggattcccc caatccaatagtacaacagttatttgaaggtcaagtaattgagaagggtaaaatagctaaaggttcattaatag gttctcaatttttaaatcaattgacatctttaatgaacttgataaatagtactgaaccacatttcatacgttgt attaaaccaaatgaaaataaaaaaccattagaatggtgtgaaccaaaaatattaattcagcttcatgccttatc aattttagaagcattagtattaagacaattaggatattcttatagaagaacctttgaagaattcttatatcaat ataaatttgtggacattgctgctgctgaagattcatcagttgaaaaccaaaataaatgtgttaatatattaaag ttgtctggactatctgaatccatgtataagataggaaaaagcatggtctttttgaaacaagaaggtgcaaaaat attgacaaaaatacaaagagagaaacttgttgaatgggaaaattgtgtgagtgtaattgaagctgctatactta aacacaaatacaaacaaaaggttaacaaaaatataccttctcttttgagagtacaagctcatataagaaaaaaa atggtagctcaataa. SEQ ID NO: 2 Plasmodium falciparum 3D7 myosin A (MyoA), amino acid sequence: XP_001350147.1, (also referred to herein as PfMyoA heavy chain) MAVTNEEIKTASKIVRRVSNVEAFDKSGSVFKGYQIWTDISPTIENDPNIMFVKCVVQQGSKKEKLTVVQIDPP GTGTPYDIDPTHAWNCNSQVDPMSFGDIGLLNHTNIPCVLDFLKHRYLKNQIYTTAVPLIVAINPYKDLGNTTN EWIRRYRDTADHTKLPPHVFTCAREALSNLHGVNKSQTIIVSGESGAGKTEATKQIMRYFASSKSGNMDLRIQT AIMAANPVLEAFGNAKTIRNNNSSRFGRFMQLVISHEGGIRYGSVVAFLLEKSRIITQDDNERSYHIFYQFLKG ANSTMKSKFGLKGVTEYKLLNPNSTEVSGVDDVKDFEEVIESLKNMELSESDIEVIFSIVAGILTLGNVRLIEK QEAGLSDAAAIMDEDMGVFNKACELMYLDPELIKREILIKVTVAGGTKIEGRWNKNDAEVLKSSLCKAMYEKLF LWIIRHLNSRIEPEGGFKTFMGMLDIFGFEVFKNNSLEQLFINITNEMLQKNFVDIVFERESKLYKDEGISTAE LKYTSNKEVINVLCEKGKSVLSYLEDQCLAPGGTDEKFVSSCATNLKENNKFTPAKVASNKNFIIQHTIGPIQY CAESFLLKNKDVLRGDLVEVIKDSPNPIVQQLFEGQVIEKGKIAKGSLIGSQFLNQLTSLMNLINSTEPHFIRC IKPNENKKPLEWCEPKILIQLHALSILEALVLRQLGYSYRRTFEEFLYQYKFVDIAAAEDSSVENQNKCVNILK LSGLSESMYKIGKSMVFLKQEGAKILTKIQREKLVEWENCVSVIEAAILKHKYKQKVNKNIPSLLRVQAHIRKK MVAQ. SEQ ID NO: 3 Plasmodium falciparum 3D7 Tetratricopeptide repeat family protein (PFUNC), putative (PF14_0196) Nucleotide sequence: XM_001348333 mRNA, CDS (also referred to herein as PFUNC, PFUNC and/or PfUnc) atgcaggaatttgttatgaatattcttagtaaagaaaaaattgggaaaatagaaaaactaaaaaatgatgggaa tgaattatatcgaaataaaaaatataaggaggctttatgtatatatgataatgctgtttgtgagttttgtggag gttcaggtgatagtttaaaaattaaggaaatggtgaaagaattttcaaaaaatgatgagactaataatataaat aaattatcagatgataataataataataatatgattgatgaaaataataagaaatgtgatttttcttatatatg tgaaattcaaaatttattcataaaaatatgccataatatatcattatgttattatttcttagaagattttgaaa aatctattgaatattgtttatatattaatgaaatgaacaataatcattataaaagttaccacacgcttgggttg tgttatgagaaattaaaagattatcaaaagagtatacattattttgataggtgtaaaatagtacttttaaaaaa tcaaaacaataaaaataaagacaataataataaaagtgaaattaatcgaattaatgaaaagttacgtgatatta tgaaaattatagatcaaaataaaaatgatccatataaaaatataagcaacattaaaaaatatcttcttgatgaa aatacaaataatataaatgacattgaagaaaataataaaaaaattaaattgttacattctatttataatcaaaa gttttatatactacttaaggaaaatatttttttatttctttttgattttattaaaaaaaataatgacatatcaa actatgacgattgcaataataataataataataataatttatatagtcataatattaatagtttattattagaa aaaacagccatttatgttatttataaaatattatccaaattagataatgaacatattattattgaaaattccaa agatgataactataataaaaatcgtaatatatgtattaacaaattagataattcaaagcttcaatattattatg atctagattatattaaaatgattttatcctttaatgaatattttacaaaagattggatatataattatataaaa aaaaaaatcaatatattagaaaatttaaagttttcaaaagatgaaaccttatataaagaacatgtagacatttt aatctatatcataaatattatgaaatatgtctatgttataaataatgattatattttaaatattattaattcct attatttaaatagcgataattctaatattaataactctggtattaatgctcttacattcttatgtaaaaaaaaa caatttttaacacaaaatagtaaggataatagaaaaaaaaaaaatgatttattagaaatgcttaaaaaagaaaa ttacttaaatatacaaaataatatacaaaataataataataataataattattatttttataagaatgaattta ttgaatttcacttttcggactctcataaatatccattgtgtatcaattccgaaatcaaaaaaattatacaaaat gttattggtatgtatgaacacttttctagtagtatagaatataccttaattttaatttttactttattacatga cccacaaagacctaaggaaaaagacatagaaatgaatgatgtaatttatgattgtatagataattattttcatc ataatgaaaatattttgatagaatggtttgtatgtattaaatgtcttttcttagtagataaaaatattatatta aattatttaataggaaaaacagaatatattgtaaaaatcttacattttattacgaactgtataggaagaaaaac taaagaagaattatccatatatatcgatgtcttattacttttattgaatatatcagaaatacgttttatgttta ctaattatattgatatgtatataaatataatgaaatctttaaattatgatcaatgctttttgaaacttttacta ggtacatttaaattatacatgcacaacatagactttaaacaacaaattcaagataatgtggatttgttctttta tgcgaaagaaatattaaagcaattcttattaacatatgataatgatgcggacggaaaaaataacacgaataatg ataaaagagaagaaaatgaggaacagacaagccatttgaattattctaatttaaattcgtacacatgctgtgtg aaaaaatgtgatgataatgatacaaagaaaaaagatattataaaccaaaagaaagatgaaaagaataagaaaca ttgtgaacttgtagataagaaaaaaaaagatcatacatatatacattcgaatatgagttgtgaaaaaacgttaa aagatttaatagaaatgttattttatttaagtttgcatattgaatttaaaaaacaattattagaggaaaaaaat aattatattttatttttcttaataaaagttggacatgatataaataaaaagaaattagataacacatataaata tatatattgcaacactataaataatttaattttaacaaaaaatgatgaaaaaataaaaagaagagaaattaata aaactaatttatcaaattttgataatgaacaaatagaagctttagaacaattttatgataaattaccaaaagaa gctagacctaaaacagatccattatatgattatggagatgaagaaacaagtaacaaattaattgatttattatt atataatgaaaaatatcaaatgaatcatattaatgataaaaataaaaataataataataataataatattaata atggtaacgtatctcctttgtcatctaaatgttcctatacaaatggtaccattatcaatattatatataacttt attaatagcaatttttttacaacaaatatagctgaatctgtatgtgaaataatttcaaagtttgttaaaaatac aaataatattggtatagttttagttaataatggattaaaaactttattattagcatctaagcatataacaaata aaaagaattgtgctttagcattaagtgaaatatttatttatacgaacccgaaacttattcatttttatgaagca tatgattctttacctttattaattgaacaactaaagagtgatgaagaattattaatctttaaaacgttaatggc aataactaatattttaactattgatgaaaatgtagcaataaaagctatgcaattaaatttatggtataaatgtt ttgatattctttcaacagaaaatgaatacataaaatctgctagcttagaatgtatatgcaatttatgttcccaa tcacatgtacatcaatatatttatgataaatatcaaacaattatgaaatcaaaaaatgaatcagataaagatat tttatttgttgatattcaaataatttattcatttaccatggaatatcaaaattataaatgtgtttttgcagcaa ctggagctttaggtatgttgtcatctgatttgcgtttgccatattatttagttagaactaaagggattgatcat attttctcatctttcaataataccaccgaccaaaatattttattacgtattttaacatttttcaacaacataat gacgtgtgatgatataccggatgatatattaaagaaaataaagacttatgtggagaaaaagaaggatttaaatg aagagaatactcaaatggcaaattttatactccagtag. SEQ ID NO: 4 Plasmodium falciparum 3D7 Tetratricopeptide repeat family protein, putative (PF14_0196) Amino acid sequence XP_001348369.1 (also referred to herein as PFUnc, PfUNC, and/or PFUNC) MQEFVMNILSKEKIGKIEKLKNDGNELYRNKKYKEALCIYDNAVCEFCGGSGDSLKIKEMVKEFSKNDETNNIN KLSDDNNNNNMIDENNKKCDFSYICEIQNLFIKICHNISLCYYFLEDFEKSIEYCLYINEMNNNHYKSYHTLGL CYEKLKDYQKSIHYFDRCKIVLLKNQNNKNKDNNNKSEINRINEKLRDIMKIIDQNKNDPYKNISNIKKYLLDE NTNNINDIEENNKKIKLLHSIYNQKFYILLKENIFLFLFDFIKKNNDISNYDDCNNNNNNNNLYSHNINSLLLE KTAIYVIYKILSKLDNEHIIIENSKDDNYNKNRNICINKLDNSKLQYYYDLDYIKMILSFNEYFTKDWIYNYIK KKINILENLKFSKDETLYKEHVDILIYIINIMKYVYVINNDYILNIINSYYLNSDNSNINNSGINALTFLCKKK QFLTQNSKDNRKKKNDLLEMLKKENYLNIQNNIQNNNNNNNYYFYKNEFIEFHFSDSHKYPLCINSEIKKIIQN VIGMYEHFSSSIEYTLILIFTLLHDPQRPKEKDIEMNDVIYDCIDNYFHHNENILIEWFVCIKCLFLVDKNIIL NYLIGKTEYIVKILHFITNCIGRKTKEELSIYIDVLLLLLNISEIRFMFTNYIDMYINIMKSLNYDQCFLKLLL GTFKLYMHNIDFKQQIQDNVDLFFYAKEILKQFLLTYDNDADGKNNTNNDKREENEEQTSHLNYSNLNSYTCCV KKCDDNDTKKKDIINQKKDEKNKKHCELVDKKKKDHTYIHSNMSCEKTLKDLIEMLFYLSLHIEFKKQLLEEKN NYILFFLIKVGHDINKKKLDNTYKYIYCNTINNLILTKNDEKIKRREINKTNLSNFDNEQIEALEQFYDKLPKE ARPKTDPLYDYGDEETSNKLIDLLLYNEKYQMNHINDKNKNNNNNNNINNGNVSPLSSKCSYTNGTIINIIYNF INSNFFTTNIAESVCEIISKFVKNTNNIGIVLVNNGLKTLLLASKHITNKKNCALALSEIFIYTNPKLIHFYEA YDSLPLLIEQLKSDEELLIFKTLMAITNILTIDENVAIKAMQLNLWYKCFDILSTENEYIKSASLECICNLCSQ SHVHQYIYDKYQTIMKSKNESDKDILFVDIQIIYSFTMEYQNYKCVFAATGALGMLSSDLRLPYYLVRTKGIDH IFSSFNNTTDQNILLRILTFFNNIMTCDDIPDDILKKIKTYVEKKKDLNEENTQMANFILQ. SEQ ID NO: 5 Plasmodium falciparum 3D7 myosin A tail domain interacting protein (MTIP) mRNA, complete cds, nucleotide sequence: XM_001350813.1 (referred to herein as Pf MTIP, Plasmodium falciparum MLC1, or Plasmodium falciparum regulatory light chain) atgaaacaagaatgcaatgtatgttattttaacttgcctgacccagagtccaccttaggtccatatgataatga attaaattatttcacttggggaccaggatttgaatatgaacctgaaccacaaagaaagccattgtcaattgaag aaagttttgaaaactctgaagaatccgaagaatcagttgctgacatacaacaacttgaagaaaaagtagatgaa agtgatgtgaggatttattttaatgaaaagagtagtggtgggaaaataagtatagacaatgcatcttacaatgc tcgaaagttaggtttagctccatcaagtatcgatgaaaagaaaattaaagaattatatggagataacttaacat atgaacaatatttagaatatttgtctatatgtgtccatgataaagataatgtagaagaacttattaaaatgttt gcacactttgataataattgtactggttacttaactaagagccaaatgaaaaatattcttacaacttggggtga tgcattaacggatcaagaagccatagatgctcttaatgccttttcatcagaagataacattgattacaaattat tctgtgaagatatattacaataa. SEQ ID NO: 6 Plasmodium falciparum 3D7 myosin A tail domain interacting protein (MTIP) amino acid sequence: XP_001350849.1 (also referred to herein as Pf MTIP, Plasmodium falciparum MLC1, or Plasmodium falciparum regulatory light chain) MKQECNVCYFNLPDPESTLGPYDNELNYFTWGPGFEYEPEPQRKPLSIEESFENSEESEESVADIQQLEEKVDE SDVRIYFNEKSSGGKISIDNASYNARKLGLAPSSIDEKKIKELYGDNLTYEQYLEYLSICVHDKDNVEELIKMF AHFDNNCTGYLTKSQMKNILTTWGDALTDQEAIDALNAFSSEDNIDYKLFCEDILQ . SEQ ID NO: 7 Plasmodium falciparum 3D7 calmodulin, putative (PF14 0181) mRNA, complete cds, nucleotide sequence: XM 001348318.1 (also referred to herein as PfELC or Plasmodium falciparum essential light chain) atgcgcatagtagataagcaaataaaagaatccttccttttagcagacagaaattttgatgggcatatttcatc gaatgaattattatacgctttaagattccttggagtggaatctgattattctctaatggaaaataaaagtgggg caacttattcaatgaatgattatgttaaaatagctaagaaacatttaggtgcacacacaccaaaagaaagaatt acaaattccttaaaaaaaatggataaaaataacaatggaactatatcagttgacgcattagttcatttagttat gactatgagtgatattttaacagaaaatgattacagaaaatttaaaaaatttgttgatcctgaaagcagaaata tcataccgttacatgtatttgtagaaaaaatactttcgtaa. SEQ ID NO: 8 Plasmodium falciparum 3D7 calmodulin, putative (PF14 0181), amino acid sequence: XP_001348354.1 (also referred to herein as PfELC (also referred to herein as PfELC or Plasmodium falciparum essential light chain) MRIVDKQIKESFLLADRNFDGHISSNELLYALRFLGVESDYSLMENKSGATYSMNDYVKIAKKHLGAHTPKERI TNSLKKMDKNNNGTISVDALVHLVMTMSDILTENDYRKFKKFVDPESRNIIPLHVFVEKILS . SEQ ID NO: 9 Plasmodium falciparum 3D7 calmodulin, putative (PF14_0181) mRNA, complete cds, nucleotide sequence: XM_001348318.1 (also referred to herein as PfCalmodulin) atgcgcatagtagataagcaaataaaagaatccttccttttagcagacagaaattttgatgggcatatttcatc gaatgaattattatacgctttaagattccttggagtggaatctgattattctctaatggaaaataaaagtgggg caacttattcaatgaatgattatgttaaaatagctaagaaacatttaggtgcacacacaccaaaagaaagaatt acaaattccttaaaaaaaatggataaaaataacaatggaactatatcagttgacgcattagttcatttagttat gactatgagtgatattttaacagaaaatgattacagaaaatttaaaaaatttgttgatcctgaaagcagaaata tcataccgttacatgtatttgtagaaaaaatactttcgtaa. SEQ ID NO: 10 Plasmodium falciparum 3D7 calmodulin, puatative (PF13_0181) amino acid sequence: XP_001348497 (also referred to herein as PfCalmodulin) MADKLTEEQISEFKEAFSLEFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEIDTDGNGTIDFPEFLTLMA RKLKDTDTEEELIEAFRVFDRDGDGYISADELRHVMTNLGEKLTNEEVDEMIREADIDGDGQINYEEFVKMMIAK. SEQ ID NO: 11 Toxoplasma gondii TPR AK Seq, TPR domain-containing protein, CDS, length = 3486 nucleotide sequence (also referred to herein as TgUNC) atggaggatttgtcaaacgctacgttagctcgcctccaggcgctgaaagaggaaggaaatgcggagtttaagcg gggcaagttcgagtccgcgatcgaagcgtattcgcgatgcctggctgatgcctcagacactctggataaagaac cagacgtcctgggaggcgcgtgtgcggccagcctctcttcctccgactctcaggtcgcagaacctcgcaaagaa agccctgccattctgaagcgcgtggccgaactgaaggcgcaaatcctgtgcaatcgcgccctgtgctaccagcg gacgaagcagttcgcggcggccgaggcggactgtacgcgcgccatcgctctccatccggcctacgtgaagagtt actaccgacgcgcggttgcgctggacgcccagggaaggcgtaaagagtgtgtggaggatctgcagacgtgtctg cgcctgcagcctggaaacaaggaggcgcaggagatgctcgcgggggttcgcgacaaggtgatgaaggaggagga gacgcgcgtcgaagagcagctgcccgagaacctgctgactgccggcctcaacgacgtgctcacggcctcgaagc gagtcgcctcccttcgccaactcggcgccttcgttcaggagcggaagctgcggcgtcagttccttcgagacggc ggtctgcgacgcgttgccgttgccctgaagagccaaatggacagtgagctcgagggcaacggccagcctcaccg gtcgctcgagtctcttccggagaccacggcctcggaccccgtggcttctgaagagagcaaaagcagcgcagacg ccgttctccccgtcagcgtcgaagcagcgtgctgggagttgctcttgtccgtcgtccagcagcaccaggcggac gacgaagacgacgcaaacaaggctctgcagacctctgtggaggccgtgaacgcgccgcttcaggtcgacgcgcc ggtcctcgagtgccgccaagctctctccggcctctggactcccaacgacttcctcgtgcgtctgcggcagctcc tgcgtgcaggcgtcgcgcgctccgacggcctcgctgcgaccgccgcgaacgaagaagctgggaaactgcggacc tgcgtgcaggcgtcgcgcgctccgacggcctcgctgcgaccgccgcgaacgaagaagctgggaaactgcggacc gtctggcgcggcgaagcctgtgacaggctcctgcgcacgatgggctgcgtggtgcagctgcaggcggcgcagtt cgacgaggacgcctccttcctcgaggcctgcgccgccggcctggagtgtatagactcccgagaggtccagcgcg cggctgtcgcggcgcttgtgggcgtcgcagacgcgcggcgccgcctgggcggcagagttgcggccgtgcggctg cggcatggactcgaaaagtgtctcgaggacgccttgcaggtcgtctcggacgcagaacacgaactcgcgggcga agacgctcgctctcagctggccaccgcgtccaagaaaagcgacagacttgaagcggtgagtcgtctacagggcc agaccgagtacttgatcatcacgctaatcgctcttctcgcagacaaagaccgcggcaaggaggagcctcccgac atgagtcgcctggtcgaccagctgctgtcgccgtacttccggccgtgcgcagaccccgaggagagcgtcgtcac cctgacagttgggttgaaggcgctgcgtttgattctgactgcggcgcgcgaagttgcgcgggcgtacctgattt ccgcgtcttcgattctcccctacctcctggctgccgccgcgggcggtgtaggtacagcgcagagcggggccgcg gggactgcagcgcatcggcgccagcaggaagctgcattggaggtcttgctggcctgcatggatttcccagaact gcgtgcgacgttgctcgaggcgaacgcggtgccggtcttcgcgaaagtgtgcagcgagagcgcgaatgtcgggt gttggatgagggcgcgtctggcggctgcactcgctcggctgtctgttcacgacgaggacgtccggatccaggta tttgactcgatcgacttctacgacgtcctcgatgtgctcgtgtcggaaattcgcgcggcaggtggcgacggccg ccaggttgcggagccgagcaccgaagccaagaacgcgcagaaaggccagccgatggctgttggagaggagacgt ttcggtctctgcttgagatcttcttcttcctcagtctccacggcgacttcaaagcgcggctcgtgaccgggaag aagggcgcgagggtgctgcggacgcttctgcaagttgcgaacggggctgggaaaaaaggcgcttcttcgagtct gacgcggtatctccttctccagagtctgtgcaacatcatgcggtcgcgagaagaccgacagagacagcggagaa ggaaaggcgaggtcggaagtccactcgcagacgttgacgacgagcagctgcagcagctcgaggagttgttcaag aagctgccggaaggcgcgaagccggctgcgaacggcgaggtcgatctcggagacaaggccctcgcaacgcagct ccgcgacatgctcctagacctgaacgtggttcatgcaatcgccgtgaacgtctgcgcgaccccgccgccgtctt ccaacgtcctgtgtgccgcggcgcaggcgctgaagttcctttgcgaggactcgcggcaccgaggcagagctgtt caggaggggggcattcggacgctcttggtggccgcgagtgggctcgaggaattcccagacgaccagaggaacgc gcgacaagctgcggcgcagctctgcatcaccaccaacccggccctgttctcttaccgcgagagcttagacctcg tcccctgcctcgcgccgcttctcaaggaccgccacgagttgctgcagtacgaaggcgcgctcgcgttgacgaat ctctgtgccctcagcgaggaggtccgcatgcgtgcgtggctcggcggcgtctgggaaggcttcgaggacctcat gttcggggagaacgagttgctgcgcgccgcggggttggagggatggtgcaacttgtcggcctcgccgacggtcc aaacggagatcgggaagaagatggaacgtttcgcggcggagaaacaagaagttcaagatatgaaactcttgctc gcgttcacgcgggaaacgaacaaccctcgtgcgcagtccgccgccgtcgcggctctcgcgatgcttctcgcgaa cgagaaggtcgcacgctgtcttccggcctacagcctctttggcaacctcgctttgagcctcgaggaagcgaagg ccgagcaggaagctctgatcgtgaggtgcgtctccgccctctacaacgtctggatcgagttgagcagttctgag gcgggagctgagacccgcatgcagatcgtgaaaaccctgcagagaaaccaacaaaaactcactggagacgcaca acacctcgccaaggaagtcctcacggcagaactctcccaagcaaacacacacacgaaagaatccaccccagact caagctaacggc. SEQ ID NO: 12 TGGT1_249480, Toxoplasma gondii GT1, tetratricopeptide repeat- containing protein, length = 1161, amino acid sequence, (also referred to herein as TgUNC) MEDLSNATLARLQALKEEGNAEFKRGKFESAIEAYSRCLADASDTLDKEPDVLGGACAASLSSSDSQVAEPRKE SPAILKRVAELKAQILCNRALCYQRTKQFAAAEADCTRAIALHPAYVKSYYRRAVALDAQGRRKECVEDLQTCL RLQPGNKEAQEMLAGVRDKVMKEEETRVEEQLPENLLTAGLNDVLTASKRVASLRQLGAFVQERKLRRQFLRDG GLRRVAVALKSQMDSELEGNGQPHRSLESLPETTASDPVASEESKSSADAVLPVSVEAACWELLLSVVQQHQAD DEDDANKALQTSVEAVNAPLQVDAPVLECRQALSGLWTPNDFLVRLRQLLRAGVARSDGLAATAANEEAGKLRT VWRGEACDRLLRTMGCVVQLQAAQFDEDASFLEACAAGLECIDSREVQRAAVAALVGVADARRRLGGRVAAVRL RHGLEKCLEDALQVVSDAEHELAGEDARSQLATASKKSDRLEAVSRLOGOTEYLIITLIALLADKDRGKEEPPD MSRLVDQLLSPYFRPCADPEESVVTLTVGLKALRLILTAAREVARAYLISASSILPYLLAAAAGGVGTAQSGAA GTAAHRRQQEAALEVLIACMDFPELRATLLEANAVPVFAKVCSESANVGCWMRARLAAALARLSVHDEDVRIQV FDSIDFYDVLDVLVSEIRAAGGDGRQVAEPSTEAKNAQKGQPMAVGEETFRSLLEIFFFLSLHGDFKARLVTGK KGARVLRTLLQVANGAGKKGASSSLTRYLLLQSLCNIMRSREDRQRQRRRKGEVGSPLADVDDEQLQQLEELFK KLPEGAKPAANGEVDLGDKALATQLRDMLLDLNVVHAIAVNVCATPPPSSNVLCAAAQALKFLCEDSRHRGRAV QEGGIRTLLVAASGLEEFPDDQRNARQAAAQLCITTNPALFSYRESLDLVPCLAPLLKDRHELLQYEGALALTN LCALSEEVRMRAWLGGVWEGFEDLMFGENELLRAAGLEGWCNLSASPTVQTEIGKKMERFAAEKQEVQDMKLLL AFTRETNNPRAQSAAVAALAMLLANEKVARCLPAYSLFGNLALSLEEAKAEQEALIVRCVSALYNVWIELSSSE AGAETRMQIVKTLQRNQQKLTGDAQHLAKEVLTAELSQANTHTKESTPDSS. SEQ ID NO: 13 Truncated Toxoplasma gondii TgUNC nucleotide sequence, CDS: atgggactcgcgggggttcgcgacaaggtgatgaaggaggaggagacgcgcgtcgaagagcagctgcccgagaa cctgctgactgccggcctcaacgacgtgctcacggcctcgaagcgagtcgcctcccttcgccaactcggcgcct tcgttcaggagcggaagctgcggcgtcagttccttcgagacggcggtctgcgacgcgttgccgttgccctgaag agccaaatggacagtgagctcgagggcaacggccagcctcaccggtcgctcgagtctcttccggagaccacggc ctcggaccccgtggcttctgaagagagcaaaagcagcgcagacgccgttctccccgtcagcgtcgaagcagcgt gctgggagttgctcttgtccgtcgtccagcagcaccaggcggacgacgaagacgacgcaaacaaggctctgcag acctctgtggaggccgtgaacgcgccgcttcaggtcgacgcgccggtcctcgagtgccgccaagctctctccgg cctctggactcccaacgacttcctcgtgcgtctgcggcagctcctgcgtgcaggcgtcgcgcgctccgacggcc tcgctgcgaccgccgcgaacgaagaagctgggaaactgcggaccgtctggcgcggcgaagcctgtgacaggctc ctgcgcacgatgggctgcgtggtgcagctgcaggcggcgcagttcgacgaggacgcctccttcctcgaggcctg cgccgccggcctggagtgtatagactcccgagaggtccagcgcgcggctgtcgcggcgcttgtgggcgtcgcag acgcgcggcgccgcctgggcggcagagttgcggccgtgcggctgcggcatggactcgaaaagtgtctcgaggac gccttgcaggtcgtctcggacgcagaacacgaactcgcgggcgaagacgctcgctctcagctggccaccgcgtc caagaaaagcgacagacttgaagcggtgagtcgtctacagggccagaccgagtacttgatcatcacgctaatcg ctcttctcgcagacaaagaccgcggcaaggaggagcctcccgacatgagtcgcctggtcgaccagctgctgtcg ccgtacttccggccgtgcgcagaccccgaggagagcgtcgtcaccctgacagttgggttgaaggcgctgcgttt gattctgactgcggcgcgcgaagttgcgcgggcgtacctgatttccgcgtcttcgattctcccctacctcctgg ctgccgccgcgggcggtgtaggtacagcgcagagcggggccgcggggactgcagcgcatcggcgccagcaggaa gctgcattggaggtcttgctggcctgcatggatttcccagaactgcgtgcgacgttgctcgaggcgaacgcggt gccggtcttcgcgaaagtgtgcagcgagagcgcgaatgtcgggtgttggatgagggcgcgtctggcggctgcac tcgctcggctgtctgttcacgacgaggacgtccggatccaggtatttgactcgatcgacttctacgacgtcctc gatgtgctcgtgtcggaaattcgcgcggcaggtggcgacggccgccaggttgcggagccgagcaccgaagccaa gaacgcgcagaaaggccagccgatggctgttggagaggagacgtttcggtctctgcttgagatcttcttcttcc tcagtctccacggcgacttcaaagcgcggctcgtgaccgggaagaagggcgcgagggtgctgcggacgcttctg caagttgcgaacggggctgggaaaaaaggcgcttcttcgagtctgacgcggtatctccttctccagagtctgtg caacatcatgcggtcgcgagaagaccgacagagacagcggagaaggaaaggcgaggtcggaagtccactcgcag acgttgacgacgagcagctgcagcagctcgaggagttgttcaagaagctgccggaaggcgcgaagccggctgcg aacggcgaggtcgatctcggagacaaggccctcgcaacgcagctccgcgacatgctcctagacctgaacgtggt tcatgcaatcgccgtgaacgtctgcgcgaccccgccgccgtcttccaacgtcctgtgtgccgcggcgcaggcgc tgaagttcctttgcgaggactcgcggcaccgaggcagagctgttcaggaggggggcattcggacgctcttggtg gccgcgagtgggctcgaggaattcccagacgaccagaggaacgcgcgacaagctgcggcgcagctctgcatcac caccaacccggccctgttctcttaccgcgagagcttagacctcgtcccctgcctcgcgccgcttctcaaggacc gccacgagttgctgcagtacgaaggcgcgctcgcgttgacgaatctctgtgccctcagcgaggaggtccgcatg cgtgcgtggctcggcggcgtctgggaaggcttcgaggacctcatgttcggggagaacgagttgctgcgcgccgc ggggttggagggatggtgcaacttgtcggcctcgccgacggtccaaacggagatcgggaagaagatggaacgtt tcgcggcggagaaacaagaagttcaagatatgaaactcttgctcgcgttcacgcgggaaacgaacaaccctcgt gcgcagtccgccgccgtcgcggctctcgcgatgcttctcgcgaacgagaaggtcgcacgctgtcttccggccta cagcctctttggcaacctcgctttgagcctcgaggaagcgaaggccgagcaggaagctctgatcgtgaggtgcg tctccgccctctacaacgtctggatcgagttgagcagttctgaggcgggagctgagacccgcatgcagatcgtg aaaaccctgcagagaaaccaacaaaaactcactggagacgcacaacacctcgccaaggaagtcctcacggcaga actctcccaagcaaacacacacacgaaagaatccaccccagactcaagctaa. SEQ ID NO: 14 Truncated Toxoplasma gondii TgUNC amino acid sequence: MGLAGVRDKVMKEEETRVEEQLPENLLTAGLNDVLTASKRVASLRQLGAFVQERKLRRQFLRDGGLRRVAVALK SQMDSELEGNGQPHRSLESLPETTASDPVASEESKSSADAVLPVSVEAACWELLLSVVQQHQADDEDDANKALQ TSVEAVNAPLQVDAPVLECRQALSGLWTPNDFLVRLRQLLRAGVARSDGLAATAANEEAGKLRTVWRGEACDRL LRTMGCVVOLQAAQFDEDASFLEACAAGLECIDSREVQRAAVAALVGVADARRRLGGRVAAVRLRHGLEKCLED ALQVVSDAEHELAGEDARSQLATASKKSDRLEAVSRLQGQTEYLIITLIALLADKDRGKEEPPDMSRLVDQLLS PYFRPCADPEESVVTLTVGLKALRLILTAAREVARAYLISASSILPYLLAAAAGGVGTAQSGAAGTAAHRRQQE AALEVLLACMDFPELRATLLEANAVPVFAKVCSESANVGCWMRARLAAALARLSVHDEDVRIQVFDSIDFYDVL DVLVSEIRAAGGDGRQVAEPSTEAKNAQKGQPMAVGEETFRSLLEIFFFLSLHGDFKARLVTGKKGARVLRTLL QVANGAGKKGASSSLTRYLLLQSLCNIMRSREDRQRQRRRKGEVGSPLADVDDEQLQQLEELFKKLPEGAKPAA NGEVDLGDKALATQLRDMLLDLNVVHAIAVNVCATPPPSSNVLCAAAQALKFLCEDSRHRGRAVQEGGIRTLLV AASGLEEFPDDQRNARQAAAQLCITTNPALFSYRESLDLVPCLAPLLKDRHELLQYEGALALTNLCALSEEVRM RAWLGGVWEGFEDLMFGENELLRAAGLEGWCNLSASPTVQTEIGKKMERFAAEKQEVQDMKLLLAFTRETNNPR AQSAAVAALAMLLANEKVARCLPAYSLFGNLALSLEEAKAEQEALIVRCVSALYNVWIELSSSEAGAETRMQIV KTLQRNQQKLTGDAQHLAKEVLTAELSQANTHTKESTPDSS. SEQ ID NO: 15 TGGT1_235470 (toxodb.org), Toxoplasma gondii GT1, CDS DNA, myosin A, TgMyoA heavy chain ATGGCGAGCAAGACCACGTCTGAGGAGCTGAAAACGGCCACGGCGCTGAAGAAGAGGTCGTCCGATGTCCACGC GGTCGACCACTCCGGCAATGTGTACAAAGGATTTCAAATCTGGACGGACTTGGCGCCGTCGGTGAAGGAGGAGC CGGACCTGATGTTTGCCAAGTGCATCGTGCAGGCGGGGACAGACAAGGGGAACTTGACCTGCGTCCAGATCGAT CCACCGGGCTTCGACGAACCGTTCGAAGTCCCGCAGGCGAATGCGTGGAACGTAAACAGCCTGATCGACCCCAT GACGTACGGAGACATCGGCATGTTGCCTCACACGAACATTCCTTGCGTCCTCGACTTCCTCAAGGTGCGCTTCA TGAAGAATCAAATCTACACGACTGCGGACCCGCTCGTCGTCGCCATCAATCCCTTCCGCGACCTCGGGAACACC ACGCTCGACTGGATTGTTCGATACAGAGACACTTTCGACCTCTCCAAACTCGCGCCCCATGTTTTCTACACCGC CCGACGCGCGCTCGACAACCTCCACGCCGTCAACAAGTCGCAAACGATCATCGTGTCCGGTGAGTCTGGCGCGG GCAAGACGGAGGCGACGAAGCAGATTATGAGGTATTTTGCGGCGGCGAAGACGGGGTCGATGGATTTGCGGATT CAGAACGCGATCATGGCGGCGAATCCAGTGCTTGAGGCATTTGGAAATGCGAAGACGATTCGCAACAACAACTC GTCGCGTTTCGGACGCTTCATGCAGCTGGATGTGGGTCGCGAAGGAGGCATCAAGTTTGGCTCCGTCGTCGCCT TTCTCCTGGAAAAGTCGCGTGTTCTCACGCAGGACGAACAGGAGCGGTCGTACCACATCTTCTACCAAATGTGC AAGGGGGCGGACGCGGCGATGAAGGAGCGCTTCCATATCCTGCCGCTCTCGGAGTACAAGTACATCAATCCGTT GTGCCTGGACGCGCCAGGGATCGACGACGTCGCGGAGTTCCACGAAGTCTGCGAGTCGTTCCGGTCGATGAATC TGACGGAGGACGAAGTCGCGAGCGTGTGGAGCATCGTGAGTGGAGTGCTGCTGCTTGGCAACGTCGAGGTGACA GCGACGAAGGATGGGGGGATCGACGACGCCGCGGCGATCGAGGGGAAGAACTTGGAGGTTTTCAAAAAGGCCTG CGGGCTGCTCTTCCTCGACGCGGAGCGCATTCGCGAAGAGCTGACGGTGAAGGTTTCGTATGCGGGGAATCAGG AGATCCGCGGCCGGTGGAAGCAGGAAGACGGAGACATGCTCAAGTCGTCGCTCGCGAAGGCGATGTACGACAAG TTGTTCATGTGGATCATTGCCGTGTTGAACCGCAGCATCAAGCCTCCGGGCGGCTTCAAGATCTTCATGGGCAT GCTCGACATCTTCGGCTTCGAAGTCTTCAAGAACAACTCGCTGGAGCAGTTCTTCATCAACATCACGAACGAAA TGCTGCAGAAGAACTTCGTCGACATCGTCTTCGACCGCGAGAGCAAGCTGTATCGTGACGAGGGTGTCTCCTCC AAGGAGTTGATTTTCACCTCGAACGCAGAAGTGATCAAGATCTTGACGGCGAAGAACAACTCGGTGCTCGCTGC GCTCGAGGACCAGTGCCTCGCCCCTGGAGGCAGCGACGAAAAGTTCCTCTCGACCTGCAAGAACGCGCTGAAAG GAACCACCAAGTTCAAGCCTGCGAAGGTCTCTCCGAACATCAATTTCCTCATCTCGCACACTGTCGGCGACATC CAGTACAACGCCGAAGGCTTCCTCTTCAAAAACAAAGATGTCCTGCGAGCAGAAATCATGGAAATCGTGCAGCA AAGCAAGAACCCCGTCGTCGCGCAACTCTTCGCTGGCATCGTCATGGAGAAGGGGAAGATGGCCAAGGGACAAC TGATTGGGTCGCAGTTCCTCTCGCAGCTGCAGAGCCTCATGGAACTTATCAACAGCACCGAGCCTCACTTCATT CGCTGCATCAAGCCGAACGACACGAAGAAGCCCCTCGACTGGGTGCCGTCGAAAATGCTCATTCAGCTGCACGC GCTCTCCGTCCTCGAGGCTCTTCAGCTCCGTCAACTCGGCTACTCTTACAGACGTCCGTTCAAGGAGTTCCTCT TCCAGTTCAAGTTTATCGACCTCTCGGCTTCTGAAAATCCAAATCTGGACCCCAAAGAAGCTGCGCTGAGACTC CTCAAAAGCAGCAAACTGCCCAGCGAAGAATACCAGCTCGGGAAGACAATGGTTTTCCTCAAGCAGACGGGCGC GAAAGAACTGACGCAGATTCAGAGAGAATGCCTTTCTTCTTGGGAGCCTCTCGTCTCAGTGCTCGAGGCGTACT ACGCTGGCAGACGCCACAAGAAGCAGCTGCTGAAAAAGACCCCCTTCATCATTCGCGCCCAGGCTCACATCCGC AGACACCTGGTGGACAACAACGTCAGCCCCGCGACTGTTCAGCCGGCGTTCTAG. SEQ ID NO: 16 TGGT1_235470 (toxodb.org), Toxoplasma gondii GT1, amino acid sequence, myosin A, TgMyoA heavy chain MASKTTSEELKTATALKKRSSDVHAVDHSGNVYKGFQIWTDLAPSVKEEPDLMFAKCIVQAGTDKGNLTCVQID PPGFDEPFEVPQANAWNVNSLIDPMTYGDIGMLPHTNIPCVLDFLKVRFMKNQIYTTADPLVVAINPFRDLGNT TLDWIVRYRDTFDLSKLAPHVFYTARRALDNLHAVNKSQTIIVSGESGAGKTEATKQIMRYFAAAKTGSMDLRI QNAIMAANPVLEAFGNAKTIRNNNSSRFGRFMQLDVGREGGIKFGSVVAFLLEKSRVLTQDEQERSYHIFYQMC KGADAAMKERFHILPLSEYKYINPLCLDAPGIDDVAEFHEVCESFRSMNLTEDEVASVWSIVSGVLLLGNVEVT ATKDGGIDDAAAIEGKNLEVFKKACGLLFLDAERIREELTVKVSYAGNQEIRGRWKQEDGDMLKSSLAKAMYDK LFMWIIAVLNRSIKPPGGFKIFMGMLDIFGFEVFKNNSLEQFFINITNEMLQKNFVDIVFDRESKLYRDEGVSS KELIFTSNAEVIKILTAKNNSVLAALEDQCLAPGGSDEKFLSTCKNALKGTTKFKPAKVSPNINFLISHTVGDI QYNAEGFLFKNKDVLRAEIMEIVQQSKNPVVAQLFAGIVMEKGKMAKGQLIGSQFLSQLQSLMELINSTEPHFI RCIKPNDTKKPLDWVPSKMLIQLHALSVLEALQLRQLGYSYRRPFKEFLFQFKFIDLSASENPNLDPKEAALRL LKSSKLPSEEYQLGKTMVFLKQTGAKELTQIQRECLSSWEPLVSVLEAYYAGRRHKKQLLKKTPFIIRAQAHIR RHLVDNNVSPATVQPAF. SEQ ID NO: 17 TgMLC1 (ToxoDB TgGT1_257680, toxodb.org) CDS DNA, myosin light chain MLC1 atgagcaaggtcgagaagaaatgcccggtgtgctaccagaagctgccgaacccggcagatgttctgggtccgat ggacaaggagttgaactatttcatgtggatgccaggcttcgagtggcgcccggaaccgaaggtgggggagtacg atggtgcctgtgagtcgccctcttgccgcgagggggggcgccctgcggcagacgaagacatgcaggaggctctc gaggagatggtggaggccgacgaaatgtatgcgcgcttcaacgcgagagcttccggaggaaaggtatccacggg agacgccatgattctcgcgcgccagctcggacttgccccgtcctacgcagacaaacaggcctttgaggaaaaga gcggcgacaaccttgactacgccagcttccagaaattcgttggcaccagcacccaccccgaagacaacatcgag gacctcgtcgaagccttcgcatactttgacgtctctaagcacggttacctgacgcgcaagcagatggggaacat cctcatgacctacggagagcctctcaccacagaagagtttaatgccttggctgcggagtacttcacaagtgacc agatcgactacaggcaattctgcaaggcaatgctcgagcgaagggagtaa. SEQ ID NO: 18 TgMLC1 (ToxoDB TgGT1_257680, toxodb.org) amino acid sequence, myosin light chain MLC1 MSKVEKKCPVCYQKLPNPADVLGPMDKELNYFMWMPGFEWRPEPKVGEYDGACESPSCREGGRPAADEDMQEAL EEMVEADEMYARFNARASGGKVSTGDAMILARQLGLAPSYADKQAFEEKSGDNLDYASFQKFVGTSTHPEDNIE DLVEAFAYFDVSKHGYLTRKQMGNILMTYGEPLTTEEFNALAAEYFTSDQIDYRQFCKAMLERRE. SEQ ID NO: 19 TGGT1_269442, Toxoplasma gondii gt1, putative calmodulin, cds, length = 264 atgtcaatggcgtggcctgattttgaggcgtggatgtcgaagaaactggcgtcctacaaccctgaggaggagtt gatcaaatctttcaaggcttttgaccggtcgaacgacggcaccgtgtctgcggacgagctttctcaagttatgc tcgctctcggcgagttgctttccgacgaagaagtcaaggccatgatcaaggaagccgacccgaacggcactggc aagatccagtacgccaactttgtcaagatgctgctgaaataa. SEQ ID NO: 20: TGGT1_269442, Toxoplasma gondii gt1, putative calmodulin, amino acid sequence MSMAWPDFEAWMSKKLASYNPEEELIKSFKAFDRSNDGTVSADELSQVMLALGELLSDEEVKAMIKEADPNGTG KIQYANFVKMLLK. SEQ ID NO: 21 A biotin acceptor site amino acid sequence SMEAPAAAEISGHIVRSPMVGTFYRTPSPDAKAFIEVGQKVNVGDTLCIVEAMKMMNQIEADKSGTVKAILVES GQPVEFDEPLVVIERS. SEQ ID NO: 22 A Myc tag amino acid sequence EQKLISEEDL. SEQ ID NO: 23 A Tyl tag amino acid sequence EVHTNQDPLD. SEQ ID NO: 24 Plasmodium falciparum motor domain amino acid sequence; PfMyoA heavy chain ending at Lys 773 MAVTNEEIKTASKIVRRVSNVEAFDKSGSVFKGYQIWTDISPTIENDPNIMFVKCVVQQGSKKEKLTVVQIDPP GTGTPYDIDPTHAWNCNSQVDPMSFGDIGLLNHTNIPCVLDFLKHRYLKNQIYTTAVPLIVAINPYKDLGNTTN EWIRRYRDTADHTKLPPHVFTCAREALSNLHGVNKSQTIIVSGESGAGKTEATKQIMRYFASSKSGNMDLRIQT AIMAANPVLEAFGNAKTIRNNNSSREGREMQLVISHEGGIRYGSVVAFLLEKSRIITQDDNERSYHIFYQFLKG ANSTMKSKFGLKGVTEYKLLNPNSTEVSGVDDVKDFEEVIESLKNMELSESDIEVIFSIVAGILTLGNVRLIEK QEAGLSDAAAIMDEDMGVFNKACELMYLDPELIKREILIKVTVAGGTKIEGRWNKNDAEVLKSSLCKAMYEKLF LWIIRHLNSRIEPEGGEKTFMGMLDIFGFEVEKNNSLEQLFINITNEMLQKNFVDIVFERESKLYKDEGISTAE LKYTSNKEVINVLCEKGKSVLSYLEDQCLAPGGTDEKFVSSCATNLKENNKFTPAKVASNKNFIIQHTIGPIQY CAESFLLKNKDVLRGDLVEVIKDSPNPIVQQLFEGQVIEKGKIAKGSLIGSQFLNQLTSLMNLINSTEPHFIRC IKPNENKKPLEWCEPKILIQLHALSILEALVLRQLGYSYRRTFEEFLYQYKFVDIAAAEDSSVENQNKCVNILK LSGLSESMYKIGKSMVFLKQEGAKILTKIQREK. SEQ ID NO: 25 Toxoplasma gondii motor domain amino acid sequence; TgMyoA heavy chain ending at Cys 775 MASKTTSEELKTATALKKRSSDVHAVDHSGNVYKGFQIWTDLAPSVKEEPDLMFAKCIVQAGTDKGNLTCVQID PPGFDEPFEVPQANAWNVNSLIDPMTYGDIGMLPHTNIPCVLDFLKVRFMKNQIYTTADPLVVAINPFRDLGNT TLDWIVRYRDTFDLSKLAPHVEYTARRALDNLHAVNKSQTIIVSGESGAGKTEATKQIMRYFAAAKTGSMDLRI QNAIMAANPVLEAFGNAKTIRNNNSSREGREMQLDVGREGGIKEGSVVAELLEKSRVLTQDEQERSYHIFYQMC KGADAAMKERFHILPLSEYKYINPLCLDAPGIDDVAEFHEVCESFRSMNLTEDEVASVWSIVSGVLLLGNVEVT ATKDGGIDDAAAIEGKNLEVEKKACGLLELDAERIREELTVKVSYAGNQEIRGRWKQEDGDMLKSSLAKAMYDK LFMWIIAVLNRSIKPPGGFKIFMGMLDIFGFEVEKNNSLEQFFINITNEMLQKNEVDIVEDRESKLYRDEGVSS KELIFTSNAEVIKILTAKNNSVLAALEDQCLAPGGSDEKFLSTCKNALKGTTKFKPAKVSPNINFLISHTVGDI QYNAEGFLEKNKDVLRAEIMEIVQQSKNPVVAQLFAGIVMEKGKMAKGQLIGSQFLSQLQSLMELINSTEPHFI RCIKPNDTKKPLDWVPSKMLIQLHALSVLEALQLRQLGYSYRRPFKEFLFQFKFIDLSASENPNLDPKEAALRL LKSSKLPSEEYQLGKTMVFLKQTGAKELTQIQREC. SEQ ID NO: 26 Plasmodium falciparum motor domain including the ELC binding site, amino acid sequence, PfMyoA heavy chain ending at Asn798 MAVTNEEIKTASKIVRRVSNVEAFDKSGSVFKGYQIWTDISPTIENDPNIMFVKCVVQQGSKKEKLTVVQIDPP GTGTPYDIDPTHAWNCNSQVDPMSFGDIGLLNHTNIPCVLDFLKHRYLKNQIYTTAVPLIVAINPYKDLGNTTN EWIRRYRDTADHTKLPPHVFTCAREALSNLHGVNKSQTIIVSGESGAGKTEATKQIMRYFASSKSGNMDLRIQT AIMAANPVLEAFGNAKTIRNNNSSREGREMQLVISHEGGIRYGSVVAFLLEKSRIITQDDNERSYHIFYQFLKG ANSTMKSKFGLKGVTEYKLLNPNSTEVSGVDDVKDFEEVIESLKNMELSESDIEVIFSIVAGILTLGNVRLIEK QEAGLSDAAAIMDEDMGVFNKACELMYLDPELIKREILIKVTVAGGTKIEGRWNKNDAEVLKSSLCKAMYEKLF LWIIRHLNSRIEPEGGEKTFMGMLDIFGFEVEKNNSLEQLFINITNEMLQKNFVDIVFERESKLYKDEGISTAE LKYTSNKEVINVLCEKGKSVLSYLEDQCLAPGGTDEKFVSSCATNLKENNKFTPAKVASNKNFIIQHTIGPIQY CAESFLLKNKDVLRGDLVEVIKDSPNPIVQQLFEGQVIEKGKIAKGSLIGSQFLNQLTSLMNLINSTEPHFIRC IKPNENKKPLEWCEPKILIQLHALSILEALVLRQLGYSYRRTFEEFLYQYKFVDIAAAEDSSVENQNKCVNILK LSGLSESMYKIGKSMVFLKQEGAKILTKIQREKLVEWENCVSVIEAAILKHKYKQKVN. SEQ ID NO: 27 Toxoplasma gondii motor domain including the ELC binding site, amino acid sequence, TgMyoA heavy chain ending at Leu 800 MASKTTSEELKTATALKKRSSDVHAVDHSGNVYKGFQIWTDLAPSVKEEPDLMFAKCIVQAGTDKGNLTCVQID PPGFDEPFEVPQANAWNVNSLIDPMTYGDIGMLPHTNIPCVLDFLKVRFMKNQIYTTADPLVVAINPFRDLGNT TLDWIVRYRDTFDLSKLAPHVFYTARRALDNLHAVNKSQTIIVSGESGAGKTEATKQIMRYFAAAKTGSMDLRI QNAIMAANPVLEAFGNAKTIRNNNSSRFGRFMQLDVGREGGIKFGSVVAFLLEKSRVLTQDEQERSYHIFYQMC KGADAAMKERFHILPLSEYKYINPLCLDAPGIDDVAEFHEVCESFRSMNLTEDEVASVWSIVSGVLLLGNVEVT ATKDGGIDDAAAIEGKNLEVFKKACGLLFLDAERIREELTVKVSYAGNQEIRGRWKQEDGDMLKSSLAKAMYDK LFMWIIAVLNRSIKPPGGFKIFMGMLDIFGFEVFKNNSLEQFFINITNEMLQKNFVDIVFDRESKLYRDEGVSS KELIFTSNAEVIKILTAKNNSVLAALEDQCLAPGGSDEKFLSTCKNALKGTTKFKPAKVSPNINFLISHTVGDI QYNAEGFLFKNKDVLRAEIMEIVQQSKNPVVAQLFAGIVMEKGKMAKGQLIGSQFLSQLQSLMELINSTEPHFI RCIKPNDTKKPLDWVPSKMLIQLHALSVLEALQLRQLGYSYRRPFKEFLFQFKFIDLSASENPNLDPKEAALRL LKSSKLPSEEYQLGKTMVFLKQTGAKELTQIQRECLSSWEPLVSVLEAYYAGRRHKKQLL. SEQ ID NO: 28 C. elegans Unc45b amino acid sequence (Genbank Accession No. AAD01976.1) mvarvqtaee irdegnaavk dqdyikadel ytealqlttd edkalrpvly rnramarlkr ddfegaqsdc tkalefdgad vkalfrrsla reqlgnvgpa fqdakealrl spndkgivev lqrlvkannd kikqttslan kvtdmeklaf rgeakdteqk mtalnnllvl cresesgatg vwnqgalvpf vinlindase neevtvtair ildetiknsv rcmkflamhd pdgpksvrfv crlmckkstk dfvdatgilv qrvfnamakm drqkemkpdp evaeankiwi irvllelqem lqdpkvgavq retcidlflk nlmhmdggip rgwswkfvee rgllalldva sqipelceyp vsaetrqhva iclqrleedm vfdtkrtifk ekvdmffnal isrctnddeg hkyriklscf litmlqgpvd iginlitndq ltpimlemaa sqdhlmqgia aelivatvsk herainmlkv gipvlralyd sedptvkvra lvglckigaa ggddiskatm keeavislak tckkfllete kysvdirrya ceglsylsld advkewivdd slllkalvll akkagalcvy tlatiyanls nafekpkvde emvklaqfak hhvpethpkd teeyvekrvr alveegavpa cvaysktesk naleliarsl lafaeyedlr griiaeggtv lclrltkeas gegkikagha iaklgakadp misfpgqray evvkplcdll hpdvegkany dslltltnla sysdsirgri lkekaipkie efwfmtdheh lraaaaelll nllffekfye etvapgtdrl klwvlysaev eeerlsrasa agfailtede nacarimdei kswpevfkdi amhedaetqr rglmgianim hssnklcsei vssevfrvlv avtklgtinq eragsteqak rgleaaekfg likatdreiy erenqmstiq e. SEQ ID NO: 29 Podospora anserina CRO1 amino acid sequence (Genbank Accession No. CAA76144.1) matvaeaaaa apeplgrldq tllifaglme ggkedeetvr elgeltrlln ddvevtkkge tsvttvidsd cvdtilcyld mrqpdvvrah aalctsaylk aagedggkkl aeffhdrvrr gtyddyivaf cvaatifpiv pdltselfls egflaslgpl mrrkwksrkv etaclemina acmnsacrea vqkyctewle eiveqdpdda vksmhtvdpd mhlqegsism rrhslqvqnl aavvlaklra vpstaatagp eariqpatts iedlskrftr mlldedeieh vqpsieglay aslqpkvkes lskdsktlkr lvkaldeapp rspmiygals iftnitryrp ietdeekrir qlkayanaag klqqvdpine dehvterckr vfeagltpvl ikqsksgsaa slaliisiih alstppplrg qlaqqgavrl liaawtalpe tengpkraaa qalarilist npalvfggtr pipqsaairp lasiltpdpt adrrdllptf eslmaltnla stdddtrksi irtawddvee qlfnpnsrvc taavelvcnl vqdpeqtlal fgdgspkakn rvkvivalad aedpktrsaa ggalasltgf devvravmgl ergvevvlgl crderedlrh rgavvvrnmv fsegevgrla rgklveggav ealmecakgs krrevvevvv qaaeglmgeg gk. SEQ ID NO: 30 S. cerevisiae She4p amino acid sequence (Genbank Accession No. DAA10818.1) mplcekgndp idsstidslc aafdktlkst pdvqkyndai ntifqlrqks esgkmpadlt nsealkdrqk ieeiltrsyq dhsesrvhls kliqndipfa lnlfeilsrs sihvfvgcfs nkdatialln elqirihyge dthvtyllsi ilqllnkfky nfkevrflvk elilrisede vksmmliifa elqssfqkdf dkavvdfmss liveaeidvg ndplsiivkt lselypsltt lcseifltkg lsklfkkrvf eeqdlqftke llrllssaci detmrtyite nylqllersl nvedvqiysa lvlvktwsft kltcinlkql seifinaisr rimpkienvn esavkleevp kvemsveala ylslkasvki mirsnesfte illtmiksqk mthclygllv imanlstlpe esngssqsin dlknyadlkg pgadkvgaek eskedillfn ekyilrteli sflkremhnl spnckqqvvr viynitrskn fipqcisqgg ttiileylan kqdigepiri lgcraltrml iftnpglifk kysalnaipf lfellprstp vddnplhnde qikltdnyea llaltnlass etsdgeevck hivstkvyws tienlmlden vplqrstlel isnmmshplt iaakffnlen pqslrnfnil vkllqlsdve sqravaaifa niattiplia kelltkkeli enaiqvfadq iddielrqrl lmlffglfev ipdngtnevy pllqenqklk dalnmslkrg dsgpefsaai pvilakikv. SEQ ID NO: 31 Drosophila melanogaster UNC-45 amino acid sequence (DmUNC) (Genbank Accession No. AAK93568) mtntinseev sdagsykdkg neafkasrwe eavehygkai kagskhkela vfyknraaay lklgkyenav edcteslkaa pgdpkalfrr aqayealekf eeaykdatal fkadpgnktv qpmlqrlhvv veersarnak tstkvkqmmd ltfdlatpid krraaannlv vlakeqtgae llykdhciak vasltkvekd qdiyvnmvhl vaalcensve rtkgvltelg vpwfmrvldq khencvstaq fclqtilnal sglknkpdsk pdkelctrnn reidtlltcl vysitdrtis gaardgviel itrnvhytal ewaerlveir glcrlldvcs eledykyesa mditgsssti asvclariye nmyydeakar ftdqideyik dkllapdmes kvrvtvaita llngpldvgn qvvaregilq milamattdd elqqrvacec liaasskkdk akalceqgvd ilkrlyhskn dgirvralvg lcklgsyggq daairpfgdg aalklaeacr rflikpgkdk dirrwaadgl ayltldaeck ekliedkasi halmdlargg nqsclygvvt tfvnlcnaye kqemlpemie lakfakqhip eehelddvdf inkritvlan egittalcal akteshnsqe liarvinavc glkelrgkvv qeggvkallr malegtekgk rhatqalari gitinpevsf sgqrsldvir pllnllqqdc talenfeslm altnlasmne svrqriikeq gvskieyylm edhlyltraa aqclonlvms edvikmfegn ndrvkflall cededeetat acagalaiit sysvkcceki laiaswldil htlianpspa vqhrgiviil nminageeia kklfetdime llsglgqlpd dtrakareva tqclaaaery riiersdnae ipdvfaensk iseiidd. SEQ ID NO: 42 Truncated PfLINC lacking N-terminal TPR domain (Genbank Accession No. XP_001348369.1 beginning at N178) NKDNNNKSEINRINEKLRDIMKIIDQNKNDPYKNISNIKKYLLDENTNNINDIEENNKKIKLLHSIYNQKFYIL LKENIFLFLFDFIKKNNDISNYDDCNNNNNNNNLYSHNINSLLLEKTAIYVIYKILSKLDNEHIIIENSKDDNY NKNRNICINKLDNSKLQYYYDLDYIKMILSFNEYFTKDWIYNYIKKKINILENLKFSKDETLYKEHVDILIYII NIMKYVYVINNDYILNIINSYYLNSDNSNINNSGINALTFLCKKKQFLTQNSKDNRKKKNDLLEMLKKENYLNI QNNIQNNNNNNNYYFYKNEFIEFHFSDSHKYPLCINSEIKKIIQNVIGMYEHFSSSIEYTLILIFTLLHDPQRP KEKDIEMNDVIYDCIDNYFHHNENILIEWFVCIKCLFLVDKNIILNYLIGKTEYIVKILHFITNCIGRKTKEEL SIYIDVLLLLLNISEIRFMFTNYIDMYINIMKSLNYDQCFLKLLLGTFKLYMHNIDFKQQIQDNVDLFFYAKEI LKQFLLTYDNDADGKNNTNNDKREENEEQTSHLNYSNLNSYTCCVKKCDDNDTKKKDIINQKKDEKNKKHCELV DKKKKDHTYIHSNMSCEKTLKDLIEMLFYLSLHIEFKKQLLEEKNNYILFFLIKVGHDINKKKLDNTYKYIYCN TINNLILTKNDEKIKRREINKTNLSNFDNEQIEALEQFYDKLPKEARPKTDPLYDYGDEETSNKLIDLLLYNEK YQMNHINDKNKNNNNNNNINNGNVSPLSSKCSYTNGTIINIIYNFINSNFFTTNIAESVCEIISKFVKNTNNIG IVLVNNGLKTLLLASKHITNKKNCALALSEIFIYTNPKLIHFYEAYDSLPLLIEQLKSDEELLIFKTLMAITNI LTIDENVAIKAMQLNLWYKCFDILSTENEYIKSASLECICNLCSQSHVHQYIYDKYQTIMKSKNESDKDILFVD IQIIYSFTMEYQNYKCVFAATGALGMLSSDLRLPYYLVRTKGIDHIFSSFNNTTDQNILLRILTFFNNIMTCDD IPDDILKKIKTYVEKKKDLNEENTQMANFILQ. SEQ ID NO: 43 PfGAP 45 Plasmodium falciparum GAP45 Sequence, CDS, Genbank Accession No. XM_001350588.1 atgggaaataaatgttcaagaagcaaagtaaaggaacccaaacgtaaagatattgatgaattagctgaac gtgaaaatttaaaaaaacaatctgaagaaataattgaagaaaaaccagaagaagttgttgagcaagtaga agaaacacatgaagaacctcttgaacaagaacaggaactggatgaacagaaaatagaagaagaagaagaa gaacctgaacaagtaccaaaagaagaaatagattatgcaactcaagaaaataaatcatttgaagaaaaac atttagaagatttagaaagatctaattcagatatttattcagaatctcaaaaatttgataatgctagtga taaattagaaacaggaactcaattaaccttatctactgaagccactggtgccgtacaacaaataactaaa ttaagtgaacccgcccatgaagaaagtatatattttacttatagatctgtaacaccttgtgatatgaata aactcgatgaaaccgctaaagttttttcaagaagatgtggatgtgatcttggtgaacgtcatgatgaaaa tgcatgtaaaatttgtagaaaaattgatttatccgatacacctttattgagctaa. SEQ ID NO: 44 PfGAP 45 Plasmodium falciparum GAP45 amino acid sequence; Genbank Accession No. XP_001350624.1 MGNKCSRSKVKEPKRKDIDELAERENLKKQSEEIIEEKPEEVVEQVEETHEEPLEQEQELDEQKIEEEEE EPEQVPKEEIDYATQENKSFEEKHLEDLERSNSDIYSESQKFDNASDKLETGTQLTLSTEATGAVQQITK LSEPAHEESIYFTYRSVTPCDMNKLDETAKVFSRRCGCDLGERHDENACKICRKIDLSDTPLLS. SEQ ID NO: 45 TgGAP 45 Toxoplasma gondii GAP45 Sequence, CDS, Genbank Accession No. XM_002366039.1 gtgagatttcctttcagcgaattttgtgatctcaagagcgagaggcacaactgtatttgagaacttttgc tttttcagcgttgcacgagttttaaatctcggtgtgactgttcgaaaccctgtcatttccctccgagaag atcggtcgacggcgcgcggacaaccgcgtgcgtaaaaggtgtttgctatttcgccggggagaaaagcggc cgtaaagtcggaagacttgccagacgagacgagaaactgggtgcggcacggcatttcatcattctgtatg tgttgttttccattcgaagaaagttttgtttctcgcggcagagggaaaggcgcgcaccgaacctgcccgc agtttccggtacatccacgcacacacttcggtggctgaaacgccgcgattgttccgttcttgtgttcgcg acttcgactctctgaatcgctcccccacacatcttttgttgtcgccccctcaactttttcgcactttttc gattcgaaatgggaaacgcgtgcaagaagaacacggccaagacgccgacccggaaggaggcggaggacct ggctgagaaggagcggcaggagcgggaggcgaaggagaaggctgaggctgaagagaaggctcgcgccgaa gcggagaagaacgcagcagacaaagcggaggctgaacgtagagcggcagaggcgcgagagcgcgaagaat cagccaggaaggaggcggaggctgaggcggcccgcaaggccgaagcagaggcggctgaggccgagcgcct ccggaaggaagcagagaagaaaaaggcggaggaggcgaaacgcaaggcggaggaggagcagcgcgccgca gccgaggaagcggagcaaagagcgcgggaggaggccgagcgccgcaaagctgaagctgcggcggcagcgg agcgcgagcgccagatgcaggaggcgctgaagcaagaggaaatgtcaccgagagagaagtacgacaagtt agccagccccgaagactccgcatccgagaccacgatggcgacacagccgcagaaagtcgccgagcacagc agcgcggcggtcacagacagatcagtggtggggtacaccgtgactccatgcgacatggcatcaattgacg agacagctaagtacttgtcaaagcgctgcggttgcgacctaggcgaccaacacgacgaaaacgagtgccc tatttgccgccacatcgacttgtcggatgcacccttgttgaactgagtgcgtaactgtttctgtgttttt ctactctacggccccggcttcgggatctgtgtctgtatagcgtgcgcttataaacgcgtaaacttcgtgt ttaagaaagattagcaagggttaggacggtgaagaagagtttgggaccgtgttttttcgacaaacgtcgg gttgctagtatcgcacgtaggtgtgcactaccccgctctccatgtaggcgtagtctgtgtagcaacagga cggttggcggcaaacagaaagggaggaaatttctgcgggttcttcgagtctgagctgtcgcgaaaagctc caaaagcgaactggctccccgcagtctatgggggacgcacccgccggtaggggtgaagtggctcacaggc ttcgcccgcctgtccgtacgtgcagggcagaatcctgcccgaacgtgagaacaaccgtcattccccgtcg tcacatagttctttttctcgaccatccccacgtgacaccactggtgtgcgaatgcggcgcagcgttcgac tgtcttccgcgaaaggcgatgcttacaaacgcacgctcgcatgacatacgtgccgtaaagaggaaaccct tet. SEQ ID NO: 46 TgGAP 45 Toxoplasma gondii GAP45 amino acid sequence, Genbank Accession No. XP_002366080.1 MGNACKKNTAKTPTRKEAEDLAEKERQEREAKEKAEAEEKARAEAEKNAADKAEAERRAAEAREREESARKEAE AEAARKAEAEAAEAERLRKEAEKKKAEEAKRKAEEEQRAAAEEAEQRAREEAERRKAEAAAAAERERQMQEALK QEEMSPREKYDKLASPEDSASETTMATQPQKVAEHSSAAVTDRSVVGYTVTPCDMASIDETAKYLSKRCGCDLG DQHDENECPICRHIDLSDAPLLN. SEQ ID NO: 47 Toxoplasma gondii ELC1 nucleotide sequence, also referred to herein as TgELC1 nucleotide sequence (ToxoDB v7.3 TgGT1_107770) Atgacctgccctccccgcgtccgtgaggccttcgccctcttcgacactgacggagatggtgagatctctggccg cgacctcgtcctcgccatccgctcatgcggtgtgtctcccaccccagacgaaatcaaggcactccccatgtcaa tggcgtggcctgattttgaggcgtggatgtcgaagaaactggcgtcctacaaccctgaggaggagttgatcaaa tctttcaaggcttttgaccggtcgaacgacggcaccgtgtctgcggacgagctttctcaagttatgctcgctct cggcgagttgctttccgacgaagaagtcaaggccatgatcaaggaagccgacccgaacggcactggcaagatcc agtacgccaactttgtcaagatgctgctgaaataaggatccattgt. SEQ ID NO: 48 Toxoplasma gondii ELC1 amino acid sequence, also referred to herein as TgELC1 MTCPPRVREAFALFDTDGDGEISGRDLVLAIRSCGVSPTPDEIKALPMSMAWPDFEAWMSKKLASYNPEEELIK SFKAFDRSNDGTVSADELSQVMLALGELLSDEEVKAMIKEADPNGTGKIQYANFVKMLLK. SEQ ID NO: 49: Plasmodium falciparum 3D7 myosin light chain, (may also be referred to herein as an “essential type light chain”, an “essential light chain”, a PfELC, and/or an ELC1) putative (PFF1320c) mRNA, Genbank Accession No. XP_966255.2: MEEIINEVELTSLFNKISEGSRTIHFEDAMEIIYKMGYVPSKEDINEFNNMTKGVCSLS NIKKFCNKIRSLNYSTEGLLDIFHFYDTNKTGKISKEKLKLLFTTVGSKMSVDEMDTII NELCNNDENIDYKEFLNRILN. SEQ ID NO: 50: Plasmodium falciparum 3D7 myosin light chain (may also be referred to herein as an “essential type light chain”, an “essential light chain”, a PfELC, and/or an ELC1), putative (PFF1320c) mRNA, NCBI Reference Sequence: XM_961162.2: atggaggaaa taattaatga agtggaattg acttctcttt ttaacaagat atcagaaggg tcgagaacta tccattttga ggatgccatg gaaataatat ataaaatggg ttatgttcct tcaaaagaag atataaatga atttaacaac atgacaaaag gtgtttgttc tttatccaat ataaaaaagt tctgcaataa aataaggtca ttgaattatt ccactgaagg tttgttggat atatttcatt tttatgatac aaataaaaca ggaaaaattt ctaaagaaaa acttaaactc ttatttacaa cagttggttc aaaaatgtcg gttgatgaaa tggatacaat aataaatgaa ttatgtaata acgatgaaaa catagactat aaggaatttc taaacaggat attaaattag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B provide schematic diagrams of T. gondii myosin motor complex and subunit structure of TgMyoA. FIG. 1A shows TgMyoA (i.e., TgMyoA heavy chain with its bound light chains, TgMLC1 and TgELC1) and TgGAP45 are anchored to the inner membrane complex (IMC) via transmembrane protein TgGAP50. This multiprotein complex is referred to as the myosin motor complex. Short actin filaments are located between the parasite plasma membrane and the IMC, and are thought to be connected to ligands on the host cell surface through linker protein(s) that bind to the cytosolic tails of surface adhesins. TgMyoA (attached to the IMC) displaces the actin filaments (attached to the substrate) causing the parasite to move relative to the substrate. Note that alternative models of parasite motility are emerging (47, 48) in which TgMyoA plays a different but still important role in generating the force required for motility. Figure adapted from (12). FIG. 1B shows the subunit structure of TgMyoA. The heavy chain motor domain contains the actin and ATP binding sites, followed by the lever arm, to which the light chains TgMLC1 and TgELC1 are believed to bind. Rotation of the TgMyoA lever arm produces a power stroke that moves actin filaments and propels the parasite forward.

FIGS. 2A and 2B show schematics of the expressed proteins. FIG. 2A shows a TgMyoA heavy chain construct that contains the motor domain (red) and the light chain-binding region (black), followed by a Bio-tag and a FLAG-tag. FIG. 2B shows that TgUNC consists of three domains: TPR (at left end), central (middle section) and the UCS region (at right end), followed by a Myc tag. The three different TgUNC constructs used during coexpression with TgMyoA heavy chain are shown below the schematic.

FIG. 3 shows a Western blot of results demonstrating co-expression of TgMyoA with the chaperone TgUNC in Sf9 cells produces soluble heavy chain. Sf9 cells were co-infected with recombinant baculovirus coding for the TgMyoA heavy chain (HC) and its light chain TgMLC1. The Western blot shows the total (T) and soluble (S) protein fractions after 72 h infection in the absence (left two lanes) or presence (right two lanes) of co-expressed TgUNC. TgUNC was detected using anti-Myc antibody, while TgMyoA heavy chain was detected with anti-FLAG antibody.

FIGS. 4A and 4B provide images of an SDS-gel showing characterization of purified TgMyoA and a graph. FIG. 4A shows results of SDS-gel analysis of purified motor proteins. Lane 1, purified protein resulting from co-expression of TgMyoA heavy chain (HC), TgMLC1 light chain, and TgUNC. TgUNC only binds to unfolded protein and does not co-purify with TgMyoA. Lane 2, molecular weight standards. Lane 3, purified protein resulting from coexpression of TgMyoA heavy chain, TgMLC1 and TgELC1 light chains, and TgUNC. FIG. 4B shows a graph of results demonstrating sedimentation velocity of TgMyoA heavy chain expressed with TgMLC1. A sedimentation coefficient of 7.7S was determined by curve-fitting to one species. The symmetrical nature of the boundary indicates that a homogeneous species is present. OD, optical density.

FIG. 5 shows a graph indicating that the number of bound light chains determines the speed of actin movement in an in vitro motility assay. The Gaussian fit of speeds for TgMyoA with TgMLC1 only was 1.5±0.2 μm/s (mean±SD, n=2,341 filaments) (solid triangles), compared to 3.4±0.7 μm/s (mean±SD, n=4,774 filaments) for TgMyoA with both light chains (solid circles). Conditions: 25 mM imidazole, pH 7.5, 50 mM KCl, 1 mM EGTA, 4 mM MgCl₂, 10 mM DTT, 5 mM MgATP, 0.5-0.7% (w/v) methylcellulose, and oxygen scavengers, 30° C. Addition of 1.2 mM calcium (i.e., 0.2 mM free calcium) did not affect motility speed (open symbols). In the presence of calcium, TgMyoA with TgMLC1 only moved actin at 1.5±0.2 μm/s (mean±SD, n=619 filaments), and TgMyoA containing both TgMLC1 and TgELC1 moved actin at 3.3±0.6 μm/s (mean±SD, n=1,729 filaments). The values obtained in calcium versus EGTA were indistinguishable (p>0.1, Kolmogorov-Smirnov test). For each dataset, the bin with the highest speed was normalized to one for presentation purposes. Data were obtained from three protein preparations of TgMyoA with both light chains, and two protein preparations of TgMyoA with TgMLC1 only.

FIG. 6 shows immunoblot results demonstrating that both TgMLC1 and TgELC1 are bound to the same heavy chain. TgMyoA heavy chain (HC) was co-expressed in Sf9 cells with both 3×Myc-MLC1 and 3×HA-ELC1. TgMyoA was co-immunoprecipitated from cell lysates using either anti-HA antibody (to immunoprecipitate TgELC1; left panels), or anti-TgMLC1 antibody (right panels), confirming that each of the light chains bind to TgMyoA heavy chain. Furthermore, TgMLC1 is present in the TgELC1 pulldowns and vice versa, demonstrating that the two light chains are simultaneously present on the same MyoA heavy chain. TgUNC (˜126 kDa) was detected with anti-Myc antibody, TgMyoA heavy chain (˜104 kDa) with anti-FLAG, 3×Myc-TgMLC1 (˜29 kDa) with anti-Myc on left panels, anti TgMLC1 on right panels and 3×HA-ELC1 (˜18 kDa) with anti-HA.

FIGS. 7A and 7B provide graphs of results of in vitro motility and steady-state actin-activated ATPase assays. FIG. 7A shows in vitro motility speed as a function of MgATP concentration. Solid line is a fit to Michaelis-Menten kinetics. Vmax=4.6±0.3 μm/s and KM=1.3±0.3 mM MgATP. FIG. 7B shows steady-state actin-activated ATPase assay as a function of skeletal actin concentration. Data were fit to the Michaelis-Menten equation: Vmax=84±9.5 s−1 and Km=136±22 04. Conditions: 10 mM imidazole, pH 7.0, 5 mM NaCl, 1 mM MgCl₂, 1 mM NaN₃, 5 mM MgATP and 1 mM DTT at 30° C.

FIG. 8 shows Western blot results demonstrating that the TPR domain of TgUNC is not required for solubility of TgMyoA. Sf9 cell infections were performed with three TgUNC constructs (see FIG. 2B). Expression and solubility of TgMyoA were determined by Western blotting. Total (T) and soluble (S) fractions were probed with either anti-FLAG (top panel) for TgMyoA heavy chain (HC) or anti-Myc (bottom panel) for TgUNC and its truncations.

FIG. 9 provides a graph illustrating in vitro motility speeds of purified TgMyoA expressed with various TgUNC constructs. When TgMyoA was expressed with either full-length TgUNC or ΔTPR, the sliding speed with skeletal actin was similar: full-length TgUNC (3.4±0.7 μm/s, mean±SD, n=4,774 filaments) and ΔTPR (3.1±0.5 μm/s, mean±SD, n=2,048 filaments). Speed decreased when TgMyoA was expressed in the presence of the UCS domain only (0.7±0.2 μm/s, mean±SD, n=1,296 filaments). The bin with the highest speed was normalized to one for presentation purposes. Data were obtained from three preparations of TgMyoA co-expressed with TgUNC, two protein preparations of TgMyoA co-expressed with ΔTPR, and one protein preparation of TgMyoA co-expressed with the UCS domain.

FIG. 10 shows a multiple sequence alignment of TgUNC (ToxoDB TgGT1_249480; GenBank Accession Number EPR63428.1, SEQ ID NO:12) with the three canonical members of the UCS family of myosin chaperones, i.e., Caenorhabditis elegans Unc45b [(AAD01976.1); SEQ ID NO:28], Podospora anserina CRO1 [(CAA76144.1); SEQ ID NO:29] and Saccharomyces cerevisiae She4p [(DAA10818.1); SEQ ID NO:30]. The alignment was generated using Multalin (http://multalin.toulouse.inra.fr/multalin/) (49) and processed using BoxShade v3.31C (http://mobyle.pasteur.fr/cgi-bin/portal.py#forms::boxshade). Identical residues are highlighted in black, similar residues in grey, and the start of the three domains (TPR domain, Central domain, and UCS domain) are shown above the sequence alignment. In TgUNC, L161 marks the start of the central domain, and E682 the start of the UCS domain. The percent identity/percent similarity of full-length TgUNC with the other UCS family members are: Unc45b, 17.4/28.7; CRO1, 9.5/16.3; She4p, 9.3/17.4. Comparing only the UCS domains, the percent identity/percent similarity with TgUNC is: Unc45b, 20.4/31.1; CRO1, 17.4/27.3; She4p, 15.3%/25.3.

FIG. 11 shows an amino acid sequence comparison of ARM motif residues in Drosophila UNC-45 and TgUNC. Sequence alignment of Drosophila melanogaster UNC-45 (DmUNC) [(accession number AAK93568); SEQ ID NO:31] with TgUNC [(ToxoDB TgGT1_249480; GenBank Accession Number EPR63428.1); SEQ ID NO:12], using the program ALIGN (http://xylian.igh.cnrs.fr/bin/align-guess.cgi) (50), shows 22.5% identity. The crystal structure of DmUNC has been determined (PDB ID: 3NOW) (51). Amino acid positions that conform to the ARM repeat consensus sequence and structural requirements proposed by Andrade et al. (52) were previously identified by Lee et al. (51), and are highlighted here. 40.4% of these ARM consensus residues (63 of 156) are identical in TgUNC (also highlighted). The last five ARM motifs (17-21, motif 17 starts around Arg715) are the proposed sites of interaction with myosin (51).

DETAILED DESCRIPTION

The invention, in part, relates to methods of preparing functional class XIV myosin and use of the prepared class XIV myosin in assays such as functional assays, drug screening assays, etc. In addition, the invention in some embodiments includes methods of preparing and using class XIV myosin, which may in some embodiments be associated with one or more myosin light chains. It has now been discovered that co-expression of a class XIV heavy chain polypeptide-encoding polynucleotide expressed with a parasite co-chaperone polypeptide-encoding polynucleotide can be used to prepare a functional class XIV myosin.

Myosins make up a family of ATP-dependent motor proteins and are involved in a number of motility processes. Motor proteins are a class of molecular motors that are able to move along the surface of a suitable substrate. Motor proteins are powered by the hydrolysis of ATP and are responsible for actin-based motility. The myosin genes are part of a large superfamily of genes whose protein products share the basic properties of actin binding, ATP hydrolysis (ATPase enzyme activity), and force transduction. Virtually all eukaryotic cells contain myosin isoforms, and the structure and function of myosin is strongly conserved across species. Most myosin molecules are include three domains, (1) the head domain that binds actin and uses ATP hydrolysis to generate force to move the actin, (2) the neck domain that is a binding region for one or more myosin light polypeptide chains and can also act as a “lever” to transduce force generated by the catalytic motor domain, and (3) the tail domain. Class XIV myosins are a myosin group that is found in the Apicomplexa phylum, including, importance, including Toxoplasma gondii (toxoplasmosis) and Plasmodium spp. (malaria). TgMyoA, the class XIV myosin in T. gondii, is necessary for efficient parasite motility, for invasion into and egress from host cells, and for virulence in a mouse model of infection. The speed of actin movement by myosin depends on both the kinetics of nucleotide binding and release from the motor domain, as well as the length of the lever arm, which is determined by the number of bound light chains.

It has now been discovered that expression of functional TgMyoA in a heterologous system requires co-expression with a co-chaperone of the UCS family. In some embodiments of the invention the co-chaperone is a T. gondii co-chaperone. The motor needs to bind two light chains (TgMLC1 and TgELC1) to propel actin at fast speeds. Heterologous expression of this unique myosin is the only way to obtain sufficient purified protein for structure-function studies as well as drug testing but not limited to Aplicomplexa members Toxoplasma gondii and Plasmodium falciparum.

Expression of Class XIV Myosin

A strategy of co-expression of a co-chaperone polypeptide with a class XIV heavy chain has now been used to prepare and isolate functional TgMyoA, a class XIVa myosin from the parasite Toxoplasma gondii, in expression system cells. Functional TgMyoA, also referred to herein as a “motor protein” or a “motor complex”, is required for the parasite to efficiently move and invade host cells. The T. gondii genome contains one myosin co-chaperone of the UNC-45/Cro1/She4p (UCS) family, which is referred to herein as TgUNC. Functional protein was obtained when the TgMyoA heavy and light chain(s) were co-expressed with TgUNC. The tetra-tricopeptide repeat (TPR) domain of TgUNC was not essential to obtain fully functional myosin. It has now been identified that purified TgMyoA heavy chain complexed with its regulatory light chain (TgMLC1) moved actin in an ensemble motility assay at a speed of ˜1.5 μm/s. When a putative essential light chain (TgELC1) was also co-expressed, TgMyoA moved actin at more than twice that speed (˜3.4 μm/s). This indicated that both light chains bind to and stabilize the lever arm, which is the myosin domain that amplifies small motions at the active site into the larger motions needed to propel actin at fast speeds. These methods resulted in successful expression of milligram quantities of a class XIV myosin in a heterologous system, and the methods and the prepared class XIV myosin can be used to perform both detailed structure-function analysis of TgMyoA and to identify compounds that inhibit the class XIV myosin.

In one aspect the invention includes methods for producing a functional class XIV myosin polypeptide. The method in some embodiments may include co-expressing three or more polynucleotides in an expression-system cell, wherein the three or more polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide, one or more myosin light chain polypeptide-encoding polynucleotides, and a parasite co-chaperone polypeptide-encoding polynucleotide. In certain embodiments of the invention, the three or more polynucleotides are co-expressed in the cell under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first myosin light chain polypeptide.

Myosin Components

Some aspects of the invention include methods of preparing a functional class XIV myosin polypeptide. The term “class XIV myosin” as used herein, means a class XIV myosin heavy chain polypeptide complexed with at least one of a regulatory light chain (MLC1) and an essential light chain (ELC1). As used herein the term “complexed” or “complex” used in conjunction with myosin means binding together of various components such as a heavy chain and one or more light chain polypeptides to make up a class XIV myosin. For example, one or more light chains may bind to a myosin heavy chain, thus forming a myosin complex. Additional components and/or molecules may be included in a myosin complex include, but are not limited to actin, calmodulin, glideosome polypeptide, etc.

In certain embodiments of the invention, a functional myosin comprises a class XIV myosin heavy chain polypeptide complexed with an MLC1 polypeptide. In certain embodiments, a functional myosin of the invention comprises a class XIV myosin heavy chain polypeptide complexed with an ELC1 polypeptide. In certain embodiments, a functional myosin of the invention comprises a class XIV myosin heavy chain polypeptide complexed with an MLC1 polypeptide and an ELC1 polypeptide. MLC1 and ELC1 polypeptides may be collectively referred to herein as “light chain polypeptides”.

Heavy Chain

Prepared functional myosins of the invention may in some embodiments comprise a sequence of a Plasmodium falciparum class XIV myosin heavy chain or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Plasmodium falciparum polypeptide referred to herein as a PfMyoA heavy chain, is set forth herein as SEQ ID NO:1, which encodes the Plasmodium falciparum class XIV heavy chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:2. In some embodiments of the invention, the heavy chain in a prepared functional class XIV myosin of the invention comprises a sequence of a Toxomplasma gondii class XIV myosin heavy chain or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Toxomplasma gondii polypeptide referred to herein as a TgMyoA heavy chain, is set forth herein as SEQ ID NO:15, which encodes the Toxomplasma gondii class XIV heavy chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:16. Sequences from additional apicomplexan organisms may also be used in methods of the invention to prepare class XIV myosins. Non-limiting examples of class XIV heavy chain polypeptide-encoding polynucleotides that may be used in methods of the invention to prepare a class XIV myosin include, but are not limited to polynucleotides that encode a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium class XIV heavy chain polypeptide or a functional variant thereof.

Light Chains

Prepared functional myosins of the invention may in some embodiments comprise one, two, or more sequences of a light chain polypeptide or a variant thereof. As described herein, a light chain may be a “regulatory” light chain, referred to herein as an MLC1 polypeptide, which is also referred to in P. falciparum as Myosin A tail domain interacting protein (MTIP). In some embodiments of the invention, a regulatory light chain comprises the sequence of a Plasmodium falciparum regulatory light chain or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Plasmodium falciparum regulatory light chain polypeptide referred to herein as a MTIP light chain, is set forth herein as SEQ ID NO:5, which encodes the Plasmodium falciparum regulatory light chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:6. In some embodiments of the invention, the regulatory light chain in a prepared functional class XIV myosin of the invention comprises a sequence of a Toxomplasma gondii regulatory light chain or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Toxomplasma gondii polypeptide referred to herein as a MLC1, is set forth herein as SEQ ID NO:17, which encodes a Toxomplasma gondii MLC1 light chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:18.

As described herein, a light chain may be an “essential” light chain, referred to herein as an ELC1 polypeptide. In some embodiments of the invention, an essential light chain comprises the sequence of a Plasmodium falciparum essential light chain, or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Plasmodium falciparum essential light chain polypeptide referred to herein as an ELC1 light chain, is set forth herein as SEQ ID NO:7, which encodes the Plasmodium falciparum essential light chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:8. Another non-limiting example of a nucleotide sequence that encodes a Plasmodium falciparum essential type light chain polypeptide, which may also be referred to herein as an ELC1 light chain, is set forth herein as SEQ ID NO:50, which encodes the Plasmodium falciparum essential light chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:49. In some embodiments of the invention, the essential light chain in a prepared functional class XIV myosin of the invention comprises a sequence of a Toxomplasma gondii essential light chain or a variant thereof. A non-limiting example of a nucleotide sequence that encodes a Toxomplasma gondii essential light chain polypeptide, is set forth herein as SEQ ID NO:47, which encodes a Toxomplasma gondii essential light chain polypeptide having an amino acid sequence set forth herein as SEQ ID NO:48.

In certain embodiments of the invention, sequences from additional apicomplexan organisms may be used in methods of the invention to prepare class XIV myosins. Non-limiting examples of regulatory and/or essential light chain polypeptide-encoding polynucleotides that may be used in methods of the invention to prepare a class XIV myosin include, but are not limited to polynucleotides that encode a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium light chain polypeptide or a functional variant thereof.

It will be understood that each apicomplexan polypeptide, or variant thereof, that is included in a class XIV myosin prepared using a method of the invention may be independently selected relative to other polypeptides included in the prepared functional class XIV myosin. For example, although not intended to be limiting, in certain embodiments of the invention a class XIV myosin heavy chain sequence may be a Toxoplasma sequence, or functional variant thereof; a MLC1 sequence may be a Plasmodium sequence, or functional variant thereof; and an ELC1 sequence may be a Neospora sequence or functional variant thereof. In additional non-limiting examples, in certain embodiments of the invention, each of the class XIV myosin heavy chain sequence, a MLC1 sequence, and/or an ELC1 sequence may be a Plasmodium sequence, or functional variant thereof; each may be a Toxoplasma sequence, or functional variant thereof; each may be an Eimeria sequence, or functional variant thereof, etc.

Additional Polypeptide Components

In certain aspects of the invention, methods of preparing a functional class XIV myosin includes expressing one or more additional polypeptides with a class XIV myosin heavy chain polypeptide and one or more light chain polypeptides. Examples of additional types of polypeptides that may be expressed with the heavy chain and one or more light chains include, but are not limited to calmodulin polypeptides and Glideosome Associated Protein-45 (GAP45) polypeptides. The TgMyoA motor is located between the plasma membrane and the inner membrane complex (IMC), a double membrane that is continuous around most of the cell. TgGAP50 (a 50 kDa gliding associated protein), an integral membrane glycoprotein of the IMC, acts as a membrane receptor for the motor. TgMyoA is linked indirectly to TgGAP50 through an apicomplexan-specific N-terminal extension of its regulatory light chain, TgMLC1, and TgGAP45 (a 45 kDa gliding associated protein). A similar linkage exists in other apicomplexan parasites, for example with PfMyoA, PfMTIP, PfGAP45, and PfGAP50 in plasmodium falciparum, and equivalent polypeptides present in other apicomplexan parasites MyoA complexes. Thus, certain embodiments of the invention may include expression of a GAP45 polypeptide. Such expression may enable an expressed myosin motor complex to express an increased level of activity. In certain embodiments of the invention, inclusion of a GAP45 polypeptide may be useful in methods and systems of the invention to screen and determine class XIV myosin activity, and in methods of the invention to screen for and to assess a candidate drug or agent's ability to alter activity of a functional class XIV myosin. Disruption of the connection between the MyoA motor and GAP45, mediated by TgMLC1 (or PfMTIP) may also be detrimental for glideosome function.

In some embodiments a calmodulin polypeptide comprises an amino acid sequence of a Plasmodium falciparum putative calmodulin sequence such as the amino acid sequence set forth herein as SEQ ID NO:10, or a variant thereof. The polypeptide set forth as SEQ ID NO:10 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:9. In some embodiments the calmodulin polypeptide comprises an amino acid sequence of a Toxoplasma gondii putative calmodulin sequence such as the amino acid sequence set forth herein as SEQ ID NO: 20, or a variant thereof. The polypeptide set forth as SEQ ID NO:20 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:19. Calmodulin (and putative calmodulin) sequences, and variants thereof, from additional apicomplexan organisms may also be used in methods of the invention to prepare class XIV myosins. Non-limiting examples of calmodulin polypeptide-encoding polynucleotides that may be expressed with a myosin heavy chain and light chain(s) in methods of the invention to prepare a class XIV myosin include, but are not limited to polynucleotides that encode a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium calmodulin polypeptide or functional variant thereof.

In some embodiments a and glideosome Associated Protein-45 (GAP45) polypeptide comprises an amino acid sequence of a Plasmodium falciparum GAP45 sequence such as the amino acid sequence set forth herein as SEQ ID NO:44, or a variant thereof. The polypeptide set forth as SEQ ID NO:44 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:43. In some embodiments the GAP45 polypeptide comprises an amino acid sequence of a Toxomplasma gondii GAP45 sequence such as the amino acid sequence set forth herein as SEQ ID NO:46, or a variant thereof. The polypeptide set forth as SEQ ID NO:46 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:45. GAP45 sequences, and variants thereof, from additional apicomplexan organisms may also be used in methods of the invention to prepare class XIV myosins. Non-limiting examples of GAP45 polypeptide-encoding polynucleotides that may be expressed with a myosin heavy chain and light chain(s) in methods of the invention to prepare a class XIV myosin include, but are not limited to polynucleotides that encode a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium GAP45 polypeptide or functional variant thereof.

Co-Chaperone Molecules

It has now been discovered that by co-expressing a class XIV myosin heavy chain polypeptide, one or more light chain polypeptide(s), and a parasite co-chaperone in a suitable cell system a functional class XIV myosin can be prepared. As used herein, the term “parasite co-chaperone” means a myosin co-chaperone that is a member of the UCS (UNC-45/Cro1/She4p) family. The UCS family is a group of proteins that are necessary for a variety of myosin- and actin-dependent functions in eukaryotic organisms. Methods of the invention, in some aspects include co-expression of a class XIV myosin heavy chain and at least one light chain with a member of the UCS family or a variant thereof.

In some embodiments of the invention, a UCS family co-chaperone that is expressed with a class XIV myosin heavy chain and one or more light chains is a UNC polypeptide variant. In some embodiments of the invention, a chaperone polypeptide encoding polynucleotide sequence comprises a homolog of the sequence of the C. elegans UNC-45 sequence and may be derived from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium organism.

In some embodiments the UNC polypeptide comprises an amino acid sequence of a Plasmodium falciparum UNC sequence such as the amino acid sequence set forth herein as SEQ ID NO:4, or a variant thereof. The polypeptide set forth as SEQ ID NO:4 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:3. In some embodiments the UNC polypeptide comprises an amino acid sequence of a Toxomplasma gondii UNC sequence such as the amino acid sequence set forth herein as SEQ ID NO: 12, or a variant thereof. The polypeptide set forth as SEQ ID NO:12 may be encoded by a nucleotide sequence set forth herein as SEQ ID NO:11. In certain embodiments of the invention, a truncated UNC polypeptide may be used to prepare a class XIV myosin using methods of the invention. A non-limiting example of a truncated UNC polypeptide, and its encoding nucleotide are set forth herein as SEQ ID NO:14 and SEQ ID NO:13, respectively. UNC sequences, and variants thereof, from additional apicomplexan organisms may also be used in methods of the invention to prepare class XIV myosins. Non-limiting examples of UNC polypeptide-encoding polynucleotides that may be used as a co-chaperone in methods of the invention to prepare a class XIV myosin include, but are not limited to polynucleotides that encode a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium UNC polypeptide or functional variant thereof.

Labels/Tags

Expression constructs used in methods of the invention may comprise one or more of a detectable label, also referred to herein as a “tag”. Thus, in certain embodiments, one or more polynucleotides that each encodes a polypeptide label may be included in a construct of the invention. Examples of polypeptide labels that may be encoded by a polynucleotide sequence included in a construct of the invention include, but are not limited to: a FLAG tag, a biotin acceptor site, a Myc tag, a His tag, or a Ty1 tag. Using standard methods, a skilled artisan will be able to identify and utilize additional types of detectable labels in embodiments of methods and constructs of the invention.

Expressed Polypeptides

It will be understood that various combinations of the polypeptide components described herein as being possible to include in a prepared myosin of the invention may be utilized in methods of the invention and in myosins prepared using such methods. In a non-limiting example, expression of a class XIV myosin polypeptide with a parasite co-chaperone may be suitable to prepare a class XIV myosin for assays such as structural assessment using crystallography, etc. Similarly, in other non-limiting examples methods of the invention, in some embodiments may include (1) expression of a class XIV myosin polypeptide, a parasite co-chaperone polypeptide and a regulatory myosin light chain polypeptide; (2) expression of a class XIV myosin polypeptide, a parasite co-chaperone polypeptide, and an essential myosin light chain polypeptide; (3) expression of a class XIV myosin polypeptide, a parasite co-chaperone polypeptide, a regulatory myosin light chain polypeptide, and an essential myosin light chain polypeptide; (4) expression of a class XIV myosin polypeptide, a parasite co-chaperone polypeptide, a regulatory myosin light chain polypeptide, and calmodulin; (5) expression of a class XIV myosin polypeptide, a parasite co-chaperone polypeptide; an essential myosin light chain polypeptide, and calmodulin; etc. Additional combinations of the components including, but not limited to those described herein may be used in embodiments of methods of the invention.

Polynucleotides, Polypeptides, and Modified/Variant Sequences

One aspect of the invention involves use of nucleic acid molecules that encode components of a functional class XIV myosin, a co-chaperone, or another polypeptide that may be complexed with a class XIV myosin as prepared using methods of the invention. As used herein, the terms “nucleic acid molecule” or “polynucleotide” are intended to include DNA molecules (e.g., cDNA or genomic DNA) and RNA molecules (e.g., mRNA). A nucleic acid molecule may be single-stranded or double-stranded or may be a double-stranded DNA molecule. An “isolated” nucleic acid molecule is free of sequences that naturally flank the nucleic acid (i.e., sequences located at the 5′ and 3′ ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived. Moreover, an “isolated” nucleic acid molecule, such as a cDNA molecule, may be free of other cellular material.

The invention further encompasses nucleic acid molecules that differ from the sequences set forth herein for a class XIV myosin heavy chain, light chains, UNC, calmodulin, GAP45, etc. (and portions thereof) due to degeneracy of the genetic code and thus encode the same polypeptide as that encoded by the disclosed sequences. Accordingly, in another embodiment, an isolated nucleic acid molecule of the invention has a nucleotide sequence encoding a protein having an amino acid sequence as set forth herein as a class XIV myosin heavy chain, light chains, UNC, calmodulin, GAP45, etc. (and portions thereof).

Aspects of the invention may include expression of class XIV myosin polypeptide sequences. Non-limiting examples of polypeptide sequences that may be used in embodiments of methods of the invention, include a class XIV myosin heavy chain polypeptide, a light chain, a UNC polypeptide, calmodulin, GAP45, etc. Such polypeptide sequences may comprise a wild-type polypeptide sequence or may be a modified polypeptide sequence that is a variant of a wild-type sequence.

As used herein the term “modified” or “modification” in reference to a variant nucleic acid or polypeptide sequence refers to a change of one, two, three, four, five, six, or more nucleotides or amino acids in the sequence as compared to the sequence from which it was derived. In a non-limiting example, a modified polypeptide sequence may be identical to a wild-type polypeptide sequence except that it has one, two, three, four, five, or more amino acid substitutions, deletions, insertions, or combinations thereof. In some embodiments a modified or variant sequence may be a truncated sequence that is shorter than the sequence from which it was derived. As used herein the term “derived” and “derived from” may mean a specific sequence may be obtained from a particular source albeit not necessarily directly from that source. In some embodiments of the invention a modified or variant sequence may include one, two, three, four, or more amino acid substitutions in a wild-type apicomplexan sequence. The term “functional variant” as used herein means a modified or variant sequence that retains at least a portion of the function or activity of the sequence from which it was derived. It will be understood that sequences of functional class XIV myosins as prepared using methods of the invention may be derived from various members of the apicomplexan family and may be independently selected relative to the other sequences used in the methods. Non-limiting examples of different wild-type amino acid sequences and nucleotide sequences and variant sequences are provided herein.

Routine sequence alignment methods and techniques can be used to align two or more substantially similar apicomplexan sequences, including but not limited to sequences from Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium, etc., thus providing a means by which a corresponding location of a modification made in one sequence can be identified in another corresponding apicomplexan sequence.

A polypeptide sequence used in methods of the invention, for example a heavy chain, a light chain, an UNC polypeptide, calmodulin, GAP45, etc. may include amino acid variants (e.g., polypeptides having a modified sequence) of the naturally occurring wild-type sequences, as set forth herein. Modified polypeptide sequences may have at least about 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% residue similarity to the polypeptide sequence disclosed herein. Methods of the invention may in some embodiments, include use of homologs of polypeptides disclosed herein. Such sequence homology can be determined using standard techniques known in the art. Polypeptide and nucleotide sequences useful in embodiments of methods of the present invention include the polypeptide and nucleotide sequences provided herein and variants that have more than about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, or 98% sequence similarity to a provided sequence. The percent similarity between the two sequences is a function of the number of identical positions shared by the sequences (i.e., % similarity=number of identical positions/total number of positions×100). Such an alignment can be performed using any one of a number of well-known computer algorithms designed and used in the art for such a purpose.

Polypeptides useful in embodiments of the invention may be shorter or longer than their corresponding polypeptide sequences set forth herein. Thus, in some embodiments, a polypeptide included in a functional class XIV myosin is a full-length polypeptide or a functional fragment thereof. Similarly, one or more of a class XIV myosin heavy chain, a light chain, an UNC polypeptide, calmodulin, GAP45, or other polypeptides used in methods of the invention may be full-length polypeptides or functional fragments thereof. A fragment of a polypeptide may also be referred to herein as a truncated polypeptide.

In some aspects of the invention, substantially similar apicomplexan polypeptide sequences may have at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or 100% similarity to an apicomplexan sequence disclosed herein. Art-known alignment methods and tools can be used to align substantially similar sequences permitting positional identification of amino acids that may be modified as described herein to prepare additional polypeptides useful in methods of the invention to prepare functional class XIV myosin.

Sequence modifications can be in one or more of three classes: substitutions, insertions or deletions. These modified sequences, (which may also be referred to as variants) ordinarily are prepared by site specific mutagenesis of nucleic acids in the DNA encoding a polypeptide, using cassette or PCR mutagenesis or other techniques known in the art, to produce DNA encoding the modified polypeptide, and thereafter expressing the DNA in recombinant cell culture. Amino acid sequence variants are characterized by the predetermined nature of the variation, a feature that sets them apart from naturally occurring allelic or interspecies variation of the polypeptides used in various embodiments of the invention. Modified polypeptides used in embodiments of the invention generally exhibit the same qualitative biological activity as the naturally occurring analogue, although variants can also be selected which have modified characteristics.

A site or region for introducing an amino acid sequence modification may be predetermined, and the mutation per se need not be predetermined. For example, to optimize the performance of a mutation at a given site, random mutagenesis may be conducted at the target codon or region and the expressed modified polypeptide screened for the optimal combination of desired activity. Techniques for making substitution mutations at predetermined sites in DNA having a known sequence are well known, for example, M13 primer mutagenesis and PCR mutagenesis.

Amino acid substitutions are typically of single residues; and insertions usually will be on the order of from about 1 to 20 amino acids, although considerably larger insertions may be tolerated. Deletions may range from about 1 to about 20 residues, although in some cases deletions may be much larger. Substitutions, deletions, insertions or any combination thereof may be used to arrive at a final variant polypeptide used in methods and functional class XIV myosin of the invention. Generally these changes are done on a few amino acids to minimize the alteration of the molecule. However, larger changes may be tolerated in certain circumstances.

In some embodiments of the invention conservative amino acid substitutions are made at one or more predicted non-essential amino acid residues. A “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, a predicted nonessential amino acid residue in a polypeptide may be replaced with another amino acid residue from the same side chain family. Alternatively, in another embodiment, mutations can be introduced randomly along all or part of a polypeptide coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for activity of the resulting polypeptide to identify mutants that retain activity when expressed to prepare a class XIV myosin in an embodiment of a method of the invention. Following mutagenesis of a sequence such as a nucleotide or polypeptide sequence set forth herein, the encoded protein can be expressed with components to prepare a class XIV myosin as described herein and the activity of the polypeptide can be determined, for example using an assay such as those described herein to assess function and activity of a prepared class XIV myosin.

Variants of polypeptides set forth herein, may exhibit the same qualitative class XIV myosin functionality activity as one or more of the sequences set forth herein, such as a class XIV myosin heavy chain polypeptide, a regulatory light chain polypeptide, an essential light chain polypeptide, a UNC polypeptide, a calmodulin polypeptide, etc. but may show some altered characteristics such as altered speed of actin movement, recovery, compatibility, and toxicity, or a combination thereof. For example, the polypeptide can be modified such that when used to prepare a class XIV myosin, the prepared class XIV myosin has an increased speed of actin movement or a higher level of complexing than when using another polypeptide.

A polypeptide of the invention such as a class XIV myosin heavy chain, a regulatory light chain, an essential light chain, a UNC polypeptide, a calmodulin polypeptide, etc. can incorporate unnatural amino acids as well as natural amino acids. An unnatural amino acid can be included in a polypeptide of the invention to enhance a characteristic (such of speed of actin movement, etc.) of a class XIV myosin that prepared with the polypeptide. Some embodiments of the invention include compositions that include one or more polypeptides of the invention, including but not limited to: a class XIV myosin heavy chain, a regulatory light chain, an essential light chain, a UNC polypeptide, and a calmodulin polypeptide. A composition may also include a carrier such as a buffer, solvent, solute, etc.

Another aspect of the invention provides nucleic acid sequences that code for a polypeptide used in methods of the invention to prepare a class XIV myosin. It would be understood by a person of skill in the art that the polypeptides of the present invention can be coded for by various nucleic acids. Each amino acid in the polypeptide is represented by one or more sets of 3 nucleic acids (codons). Because many amino acids are represented by more than one codon, there is not a unique nucleic acid sequence that codes for a given protein. It is well understood by those of skill in the art how to make a nucleic acid that can code for a polypeptide of the invention by knowing the amino acid sequence of the protein. A nucleic acid sequence that codes for a polypeptide or protein is the “gene” of that polypeptide or protein. A gene can be RNA, DNA, or other nucleic acid than will code for the polypeptide. Some embodiments of the invention include compositions that include one or more nucleic acid sequences that encode a polypeptide of the invention, including but not limited to: a class XIV myosin heavy chain, a regulatory light chain, an essential light chain, a UNC polypeptide, and a calmodulin polypeptide. A composition may also include a carrier such as a buffer, solvent, solute, etc.

Amino acid and/or polynucleotide sequences that may be used in methods and expression systems of the invention, include, but are not limited to sequences that are derived from Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium amino acid and/or nucleic acid sequences. Sequences derived from sequences of various types of apicomplexan organisms can be used in methods and systems of the invention, including but not limited to Toxoplasma, including but not limited to Toxoplasma gondii; Plasmodium, including but not limited to Plasmodium falciparum, P. vivax, P. knowlesi. P. ovale, or P. malariae; Neospora, including but not limited to Neospora caninu or Neospora hughesi; Sarcocystis, including but not limited to Sarcocystis neurona, bovihominis (S. hominis,), or S. suihominis; Eimeria, including but not limited to Eimeria tenella, E. bovis, E. necatrix, E. ellipsoidalis, or E. zuernii; and Cryptosporidium, including but not limited to Cryptosporidium parvum, C. hominis, C. canis, C. felis, C. meleagridis, or C. muris. Those skilled in the art will readily recognize how to utilize sequences from these types of organisms to prepare functional class XIV myosin polypeptide using methods and systems of the invention. The term “protein” and “polypeptide” are used interchangeably herein.

Expression Systems

Vectors

Methods of the invention, in some embodiments, include use of recombinant expression systems. In embodiments of the invention, expression systems comprises host cells (prokaryotic or eukaryotic cells) that are transformed by vectors and recombinants and that are capable of expressing said RNA and/or DNA fragments. In certain aspects, the invention provides methods for preparing a functional class XIV myosin polypeptide comprising the steps of: (a) culturing a host cell containing a vector under conditions that provide for expression of the functional class XIV myosin polypeptide and (b) recovering the expressed functional class XIV myosin polypeptide sequence. This method, in some embodiments, may also include additional methods of (c) subjecting the prepared polypeptide to protein purification.

Some aspects of the invention also relate to methods for production/preparation of a recombinant functional class XIV myosin polypeptide, wherein the methods may include steps of: a) transforming an appropriate cellular host with one or more recombinant vectors, in which at least a class IX myosin heavy chain polynucleotide sequence or functional fragment thereof, a co-chaperone polynucleotide sequence or functional fragment thereof, and one or more light chain polynucleotide sequences or functional fragments thereof, have been inserted under the control of appropriate regulatory elements, b) culturing the transformed cellular host under conditions suitable for the expression of the insert, and, c) harvesting (e.g., isolating) a class XIV myosin polypeptide.

Vectors provided by the present invention may typically comprise a class IX myosin heavy chain polynucleotide sequence or functional fragment thereof, a co-chaperone polynucleotide sequence or functional fragment thereof, and one or more light chain polynucleotide sequences or functional fragments thereof encoding the desired amino acid sequence and preferably transcription and translational regulatory sequences operably linked to the amino acid encoding sequences so as to allow for the expression of the class XIV myosin polypeptide in the cell. In some embodiments of the invention, a vector will include appropriate prokaryotic, eukaryotic or viral promoter sequence followed by a nucleotide sequence as defined above. The recombinant vector of the invention may allow the expression of a class XIV myosin polypeptide in a prokaryotic, or eukaryotic host or in living mammals when injected as naked RNA or DNA.

The vector may comprise a plasmid, a cosmid, a phage, or a virus or a transgenic animal. In some embodiments of the invention, the vector is a baculovirus vector. Examples of such expression vectors and insect cell expression systems and methods are described in The Baculovirus Expression System: A Laboratory Guide, Linda King, Springer; 2012, the content of which is incorporated by reference herein. Many useful vectors are known in the art and may be obtained from such vendors as Stratagene, New England Biolabs, Promega Biotech, and others.

In certain embodiments of the invention vectors may include regulatory control sequences that allow for inducible expression of a class XIV myosin polypeptide, for example in response to the administration of an exogenous molecule. Alternatively, temporal control of expression of the class XIV myosin polypeptide may occur by only introducing the polynucleotide into the cell when it is desired to express the polypeptide.

Expression vectors may also include, for example, an origin of replication or autonomously replicating sequence and expression control sequences, a promoter, an enhancer and necessary processing information sites, such as ribosome-binding sites, RNA splice sites, polyadenylation sites, transcriptional terminator sequences, and mRNA stabilizing sequences. Secretion signals may also be included where appropriate. Vectors of the invention may be prepared using methods described herein and with additional art-known standard recombinant techniques well known in the art and discussed, for example, in Molecular Cloning: a laboratory manual, Green, M. R., J. Sambrook, 2012 Cold Spring Harbor Laboratory Press, 4^(th) Edition; The Baculovirus Expression System: A Laboratory Guide, Linda King, Springer; 2012, the content of which are incorporated by reference herein.

An appropriate promoter and other necessary vector sequences may be selected to be functional in the host, and may include, when appropriate, those naturally associated with apicomplexan (or other organism) sequences.

Expression and cloning vectors useful in embodiments of methods of the invention may contain a selectable marker, a gene encoding a protein necessary for survival or growth of a host cell transformed with the vector. The presence of this gene ensures growth of only those host cells that express the inserts. Typical selection genes encode proteins that a) confer resistance to antibiotics or other toxic substances, e.g. ampicillin, neomycin, methotrexate, etc.; b) complement auxotrophic deficiencies, or c) supply critical nutrients not available from complex media, e.g., the gene encoding D-alanine racemase for Bacilli. The choice of the proper selectable marker will depend on the host cell, and appropriate markers for different hosts are well known in the art.

Vectors containing a class XIV myosin heavy chain polynucleotide sequence or functional fragment thereof, a co-chaperone polynucleotide sequence or functional fragment thereof, and one or more light chain polynucleotide sequences or functional fragments thereof sequences can be transcribed in vitro and the resulting RNA introduced into the host cell by well-known methods, e.g., by injection, or the vectors can be introduced directly into host cells by methods well known in the art, which vary depending on the type of cellular host, including electroporation; transfection employing calcium chloride, rubidium chloride, calcium phosphate, DEAE-dextran, or other substances; microprojectile bombardment; lipofection; infection (where the vector is an infectious agent, such as a retroviral genome); and other methods. The introduction of a class XIV myosin heavy chain polynucleotide sequence or functional fragment thereof, a co-chaperone polynucleotide sequence or functional fragment thereof, and one or more light chain polynucleotide sequences or functional fragments thereof sequences into a host cell may be achieved by any method known in the art, including, inter alia, those described herein.

In certain embodiments of the invention a class XIV myosin heavy chain polynucleotide sequence or functional fragment thereof, a co-chaperone polynucleotide sequence or functional fragment thereof, and one or more light chain polynucleotide sequences or functional fragments thereof are part of a viral vector, such as a baculovirus vector, or infectious virus, such as a baculovirus. In certain embodiments of the invention, one, two, three, or more vectors are inserted into a cell for expression and in some embodiments of the invention, a viral transfer vector may be used that allows 1, 2, 3, 4, 5, or more polynucleotide sequences that a polypeptide to be inserted into the same vector so they can be co-expressed by the same recombinant virus.

Host Cells

To produce a cell capable of expressing a functional class XIV myosin polypeptide, polynucleotide sequences such as those that encode a class XIV myosin heavy chain polypeptide, a co-chaperone polypeptide, a calmodulin polypeptide, a GAP45 polypeptide, or one or more light chain polypeptides are incorporated into a recombinant vector, which is then introduced into a host prokaryotic or eukaryotic cell.

The invention, in some aspects, also provides host cells transformed or transfected with a one or more of an exogenous class XIV myosin heavy chain polynucleotide sequence, a co-chaperone polynucleotide sequence, a calmodulin polynucleotide sequence, a GAP45 polynucleotide sequence, or one or more light chain polynucleotide sequences. A host cell useful in embodiments of the invention may include but are not limited to a cell from yeast, filamentous fungi, a plant, insect, amphibian, avian species, bacteria, mammals, and human cells in tissue culture. In certain embodiments of the invention, a host cell may be a cell from E. coli, Pseudomonas, Bacillus, Streptomyces, yeast, CHO, R1.1, COS 1, COS 7, BSC1, BSC40, or BMT10 cells. In certain embodiments of the invention, a host cell is an Sf9 cell.

Large quantities of class XIV myosin polypeptide produced/prepared by expressing a class XIV myosin heavy chain polynucleotide sequence with a co-chaperone polynucleotide sequence and optionally with one or more of a calmodulin polynucleotide sequence, a GAP45 polynucleotide sequence, one or more light chain polynucleotide sequences—(or fragments of any of the listed polynucleotide sequences) in vectors or other expression vehicles in compatible prokaryotic or eukaryotic host cells.

In certain embodiments of the invention a prepared class XIV myosin polypeptide is isolated. As used herein, the term “isolated” when used in reference to a prepared polypeptide of the invention includes such polypeptides that are separated from the system in which they are expressed. Isolated prepared class XIV myosin polypeptides may be used in various assays to determine and measure activity of the myosin, to test the effect of contacting the myosin polypeptide with one or more candidate compounds, to assess function of the myosin polypeptide, etc.

Function and Assays

As used herein the term “functional” when used in regard to a class XIV myosin polypeptide means a class XIV myosin polypeptide that under suitable conditions will move actin. Actin movement may be detected and assessed using assays, such as, but not limited to, an ensemble motility assay. Such assays can be used to assess whether a prepared myosin polypeptide is functional, and also to determine a speed at which the functional myosin moves actin. In some embodiments a functional class XIV myosin moves actin at a speed of up to about 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 μm/s.

A number of different assays may be used to assess function of prepared class XIV myosin. Non-limiting examples include actin-activated APTase assays, which may include sensitive colorimetric methods that use malachite green and are compatible with high throughput plate screening, for example, 96-well plate screening. See for example Henkel, R. D., et al., (1988) Anal. Biochem. 169, 312-318. Actin pelleting methods may also be used in some aspects may include centrifugation of actin and myosin for 25 min at 350,000×g or other suitable conditions. Following centrifugation, myosin bound to actin is quantified using a method such as SDS-gel densitometry or by protein concentration determination in the supernatant. Another non-limiting example of an activity assay is an in vitro motility assay, as described in Trybus, K. M. (2000) Methods 22, 327-335. Additional assays are also suitable for determining and assessing function of a class XIV myosin, such as one prepared using a method of the invention, or other control class XIV myosins.

Methods of Activity/function Assessment

It has been identified that class XIV myosin activity may contribute to onset of infection of a subject by a parasite such as an apicomplexan organism. Function class XIV myosin prepared using methods of the invention may be useful in assays to identify compounds useful to prevent or treat an infection of a subject by a parasite such as an apicomplexan parasite. A compound that when contacted with a functional class XIV myosin reduces the myosin's activity by at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%, may be a compound useful to prevent or treat an apicomplexan infection or to prevent contamination of a substrate by an apicomplexan organism. Methods of the invention, in some embodiments, include methods of identifying a compound as a candidate compound to inhibit a parasite that expresses a class XIV myosin polypeptide.

In certain embodiments of the invention, prepared myosin of the invention may be used to assess compounds that when contacted with a functional class XIV myosin increase the myosin's activity by at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%, or more and thus enhance one or more functions or activities of an apicomplexan organism that expresses a class XIV myosin. Thus, the invention, in some embodiments, may include methods of identifying a compound as a candidate compound to enhance a parasite that expresses a class XIV myosin polypeptide.

Identification of Candidate Compounds

The invention, in some aspects also includes methods to identify candidate compounds that decrease (or increase) class XIV myosin activity when contacted with a cell, tissue, subject, or substrate. The invention, in part, may also include methods to assess the efficacy of candidate class XIV myosin activity-modulating compounds to decrease the level of expression and/or to reduce the level of an activity/function of a class XIV myosin polypeptide in a cell or organism. Such methods may be carried out in vivo in human or animal subjects; or using in vitro assays of the invention such as in cells from culture—e.g., as screening assays to assess compounds that may—modulate class XIV myosin directly or indirectly, for example by modifying level or activity of a co-chaperone, or other molecule. Such modulating compounds that directly or indirectly alter class XIV myosin polypeptide activity in a cell, tissue, or organism may be used in the treatment or prevention of an apicomplexan infection or contamination of a substrate by an apicomplexan organism.

Assays for assessing activity levels of a prepared class XIV myosin in embodiments of the invention may include determining one or more class XIV myosin levels and/or activities, including but not limited to determining levels of function/activity of components of a class XIV myosin polypeptide (e.g., a heavy chain, a light chain), or other polypeptides described herein such as a co-chaperone, calmodulin, a GAP45 polypeptide etc. that are co-expressed in methods of the invention useful to prepare a functional class XIV myosin. For example, assay methods of the invention may be used to determine whether a candidate compound interferes with (e.g., reduces) an interaction between a myosin heavy chain polypeptide and one or more light chains. In another non-limiting example of assays for candidate compounds, methods of the invention may also be used to determine whether a candidate compound interferes (e.g., reduces) an interaction between a co-chaperone and folding of the heavy chain. Such interference may reduce the function/activity of the prepared class XIV myosin and thus, contacting an apicomplexan organism with the compound may be useful to reduce the organism's ability to cause an infection and this prevent or treat an apicomplexan infection of a subject or apicomplexan contamination of a substrate.

As used herein, aspects of the invention may include assessment of interactions between component polypeptides that are part of a class XIV myosin complex or are used to prepare a functional class XIV myosin. Examples of such component polypeptides include, but are not limited to, a class XIV myosin heavy chain, a regulatory light chain, an essential light chain, calmodulin, a co-chaperone, a UCS polypeptide, a GAP45 polypeptide, etc. Assay methods of the invention may be used to assess whether a candidate compound interferes with interactions between one or more component polypeptides.

In some embodiments of the invention, a level of activity or interaction of one or more component polypeptides is measured in relation to a control level of the activity or interaction of the one or more component polypeptides. One possible measurement of the level a component polypeptide may be a measurement of an absolute level of a component polypeptide or its encoding nucleotide. This could be expressed, for example, in the level of a component polypeptide or encoding nucleotide per unit of cells or unit volume in an assay. Another measurement of a level of a component polypeptide or its encoding nucleotide may be a measurement of the change in the level of the component polypeptide or its encoding nucleotide over time. This may be expressed in an absolute amount or may be expressed in terms of a percentage increase or decrease over time.

In some aspects, the invention includes methods that provide information on the efficacy of a candidate compound to treat an apicomplexan infection or contamination. In certain aspects, the invention includes methods to assess activity and efficacy of compounds administered to a subject to prevent or treat an apicomplexan infection. Similarly, the invention in some embodiments may include methods to assess activity and efficacy of compounds contacted with an apicomplexan organism. Information about the stage or status of an infection or contamination by an apicomplexan organism and the efficacy of a compound or treatment of an infection by the organism can be used to assist a health-care provided to select a treatment for administration to a subject at risk or known to have an apicomplexan infection or can be used by a health-care professional to adjust (e.g., increase, decrease, or stop) a treatment that is being provided to such a subject.

As used herein a “subject” refers to any animal, such as, but not limited to a human, a non-human primate, a rodent, a dog, cat, bird, horse, or other animal. Thus, in addition to human medical application, some aspects of the invention include veterinary application of methods described herein.

In some aspects of the invention, methods are provided to identify candidate compounds for preventing or treating an apicomplexan infection of a subject and/or to reduce apicomplexan contamination of a substrate. Methods of the invention may be used to determine the efficacy of a compound for prevention and/or treatment of the infection or contamination. Such methods may include, for example, determining one or more levels of activity of a prepared functional class XIV myosin and contacting the class XIV myosin with a candidate compound and determining whether there is an increase, decrease, or no change in the activity of the class XIV myosin.

As described herein, a level of function/activity in a class XIV myosin prepared using methods of the invention can be determined using assay methods of the invention to measure the amount and/or activity of a prepared class XIV myosin molecule in an in vitro assay. As used herein, the term “measure” may refer to a determination of the presence or absence of activity of a prepared class XIV myosin and may refer to a determination of a level of activity of a prepared class XIV myosin. Methods of measuring activity of a class XIV myosin polypeptide are known in the art, and non-limiting examples of measuring means are provided herein.

The following examples are provided to illustrate specific instances of the practice of the present invention and are not intended to limit the scope of the invention. As will be apparent to one of ordinary skill in the art, the present invention will find application in a variety of compositions and methods.

EXAMPLES Example 1 Expression Constructs

Full length (FL) TgUNC was amplified from T. gondii cosmid #p559; (http://toxodb.org/toxo/; cosmid generously provided by Dr. M J Gubbels) using the primer pair TPRForANcoI and TPRRevAFullMycStpKpnI (see Table 1 for primer sequences). A Myctagged TgUNC PCR product was cloned into the baculovirus transfer vector pAcSG2 (BD Biosciences). TgUNC pAcSG2 was truncated to make two other constructs. TgUNCΔTPR starts at residue Leu161, eliminating the tetra-trico-peptide repeat region (TPR) but keeping the central and UCS domains along with the C-terminal Myc tag. The TgUNC UCS only construct starts with residue Glu682, thus eliminating both the TPR and central domains.

TABLE 1 List of oligonucleotides used for cloning. Primer SEQ ID Gene name Primer sequence NO TgUNC TPR cggcggtaccttacaggtcttc 32 RevAFullMyc ttcagagatcagtttctgtt STPKpnI cgcttgagtctgg. TPRForANcol agca ccatgg aggatttg 33 tcaaacgc. TgMyoA EcoR1-FLAG- gggggaattcatggactacaa 34 MyoF1 agacgatgacgacaagatggc. c-TgMyoA- gggggaattcctactactag 35 EcoRI aacgccggctgaacagtc. TgMLC1 MLC-F catggaattcatgagcaa 36 ggtcgagaaga. MLC-R catgagatcttgattactc 37 ccttcgctcgag. 6HISMLC gcacaatcatatgcatca 38 1NdeIF ccaccatcatcacagca aggtcgagaagaaatgc. MLC1BamHIR gcacaatggatccttactccctt 39 cgctcgagcatt. TgELC1 6HISELC gcacaatcatatgcatcacc 40 1NdeIF accatcat cacacctgccctccccgcgt ccgt. ELC1BamHIR gcacaatggatccttatttcag 41 cagcatcttgacaaagt.

The plasmid pEB2-FLAG-MyoA (Lucas Tilley and GEW, unpublished) was used as a template to amplify nFLAG tagged TgMyoA heavy chain (ToxoDB TgGT1_235470) using primer pair EcoR1-FLAG-MyoF1 and c-TgMyoA-EcoR1. The PCR product was cloned into the baculovirus transfer vector pAcUW51 (BD Biosciences). TgMyoA-cBio-cFLAG was constructed by digesting TgMyoA heavy chain from pVL1392FLAGTgMyoA (Aoife Heaslip and GEW, unpublished) with BamHI/EcoRV and inserting the cleavage fragment into a modified version of pAcSG2 containing both a biotin acceptor site and FLAG tag at the C-terminus.

The TgMLC1 gene (ToxoDB TgGT1_257680) was PCR amplified from parasite cDNA using primers MLC-F and MLC-R and cloned untagged by ligation of the digested, gel extracted PCR product at the EcoRI and BglII restriction sites in pAcSG2. The 6×His tagged MLC1 gene was amplified from pAcSG2 TgMLC1 (Aoife Heaslip and GEW, unpublished) using the primer pair 6HISMLCINdeIF and MLC1BamHIR. The resulting PCR product was cloned into the bacterial expression vector pET3a (Novagen).

The TgELC1 gene (ToxoDB v 7.3 TgGT1_107770) was PCR amplified from T. gondii RH strain cDNA. This entry codes for a 134 aa (˜15 kDa) protein as described in (6) and can be viewed at http://v7-3.toxodb.org/toxo.b15/showRecord.do?name=Gen eRecordClasses.GeneRecordClass&project_id=ToxoDB&source_id=TGGT1_107770 (last accessed Apr. 2, 2014). The PCR product was ligated downstream of the p10 promoter in vector pAcUW51 for baculovirus expression. In addition, a PCR product of TgELC1 with a 6×His tag using the primer pair 6HisELC1NdeIF and ELC1BamHIR was cloned into the bacterial expression vector pET3a (Novagen).

A dual light chain plasmid was constructed for immunoprecipitation studies. TgELC1 with a C terminus 3×HA tag was cloned into vector pAcUW51 downstream of the p10 promoter, while TgMLC1 with an N-terminal 3×Myc tag was cloned downstream of the polH promoter. All constructs were sequenced prior to transfection

Co-Immunoprecipitations—

Sf9 cells were harvested 72 h after infection with recombinant baculoviruses (TgMyoA heavy chain and tagged light chains), and lysed with 10 mM imidazole Ph 7.4, 150 mM NaCl, 1 mM EGTA, 5 mM MgCl2, 7% (w/v) sucrose, 3 mM NaN3, 1% (v/v) NP-40, 1 mM DTT and 1× protease inhibitor cocktail (Sigma-Aldrich, catalog# P8340). Following addition of 5 mM MgATP, the lysate was spun at 350,000×g for 20 min at 4° C. The supernatant was incubated with either rabbit anti-TgMLC1 (a generous gift from Dr. Con Beckers) or rat anti-HA (Roche #11867423001) overnight at 4° C. Rec-Protein ASepharose beads (Invitrogen) were added and the samples incubated at 4° C. for 60 min. The beads were washed four times with lysis buffer. Bound proteins were eluted by boiling in SDS-PAGE sample buffer, centrifuged at 100×g for 2 min and resolved on 4-12% gradient gels. The protein was transferred to Immobilon-FL (Millipore, Bedford, Mass.) and probed with mouse anti-Myc 9E10 (1:2,000; Developmental Studies Hybridoma Bank, University of Iowa), rat anti-HA (1:400) or rabbit anti-HA (1:2,000, AbCam #9110) and mouse anti-FLAG (1:7,500, Sigma-Aldrich). LI-COR secondary antibodies (anti-Mouse IRDye680RD, anti-Rabbit IRDye800CW and anti-Rat IRDye800CW) were used according to manufacturer's instructions and blots were scanned using an Odyssey CLx Infrared Imaging System (LI-COR, Lincoln, Nebr.).

Protein Expression and Purification—

Sf9 cells were co-infected with recombinant baculovirus coding for TgMyoA heavy chain (tagged at the Cterminus with a Bio-tag and FLAG-tag), untagged light chain(s), and the co-chaperone TgUNC. The cells were grown in media supplemented with 0.2 mg/ml biotin. After 72 hours, the cells were lysed by sonication in 10 mM imidazole, pH 7.4, 0.2 M NaCl, 1 mM EGTA, 5 mM MgCl2, 7% (w/v) sucrose, 2 mM DTT, 0.5 mM AEBSF, 5 μg/ml leupeptin, and 5 mM benzamidine. To determine TgMyoA heavy chain solubility, the extracts were centrifuged at 350,000×g for 20 min. For motor purification, 25 μg/ml each of bacterially expressed TgMLC1 and TgELC1 (see below) and 5 mM MgATP were added to the lysate, which was then clarified at 200,000×g for 30 min. The supernatant was applied to a FLAG affinity resin column (Sigma-Aldrich) and washed with 10 mM imidazole, pH 7.4, 0.2 M NaCl, 1 mM EGTA, and 1 mM NaN3. TgMyoA was eluted from the column with 0.1 mg/ml FLAG peptide in the column buffer. The fractions of interest were combined and concentrated with an Amicon centrifugal filter device (Millipore) and dialyzed against 10 mM imidazole, pH 7.4, 0.2 M NaCl, 50% (v/v) glycerol, 1 mM DTT, and 1 μg/ml leupeptin for storage at −20° C.

HIS-tagged light chains (TgELC1 or TgMLC1) in pET3a (Novagen) were expressed in BLR(DE3) competent cells grown in LB broth. The cultures were induced with 0.4 mM IPTG and grown overnight at 27° C. before being pelleted and frozen. The pellets were lysed by sonication in 10 mM sodium phosphate, pH 7.4, 0.3 M NaCl, 0.5% (v/v) glycerol, 7% (w/v) sucrose, 7 mM β-mercaptoethanol, 0.5 mM AEBSF, and 5 μg/ml leupeptin. The cell lysate was clarified at 200,000×g for 30 min. TgELC1, which is found in the supernatant, was boiled for 10 min in a double boiler, and then clarified at 26,000×g for 30 min. Soluble protein was applied to a HIS-Select® nickel affinity column (Sigma-Aldrich). Non-specifically bound protein was removed by washing the resin with buffer A (10 mM sodium phosphate, pH 7.4, 0.3 M NaCl). TgELC1 was then eluted from the column with buffer A containing 200 mM imidazole. The protein was dialyzed overnight against 10 mM imidazole, pH 7.4, 150 mM NaCl, 1 mM EGTA, 1 mM MgCl2, and 50% (v/v) glycerol.

Bacterially expressed TgMLC1 is found in the insoluble inclusion bodies. The cell lysate was clarified at 26,000×g for 10 min. The pellet was dissolved in 20 ml of 8 M guanidine, 150 mM NaCl, 10 mM NaPO₄, pH 7.5, 10 mM DTT and stirred at room temperature until dissolved. It was then clarified at 200,000×g for 30 min and dialysed overnight against 2×1 liter of buffer A containing 7 mM β-mercaptoethanol and 1 μg/ml leupeptin. The next day the sample was clarified at 26,000×g for 30 min and the supernatant was applied to a HIS-Select® nickel affinity column (Sigma-Aldrich). The column was washed with 15 ml of dialysis buffer and TgMLC1 was eluted with buffer A containing 200 mM imidazole. The protein was dialyzed overnight against 10 mM Imidazole pH 7.4, 150 mM NaCl, 1 mM EGTA, 1 mM MgCl2, and 50% (v/v) glycerol. Both purified light chains were stored at −20° C.

Gels—

Proteins were separated on a 4-12% Bis-Tris NuPAGE gel (Invitrogen) run in MES buffer, per NuPAGE technical guide.

In Vitro Motility—

To prepare the flow cell, 0.2 mg/ml biotinylated BSA in buffer B (150 mM KCl, 25 mM imidazole, pH 7.5, 1 mM EGTA, 4 mM MgCl₂, 10 mM DTT) was added to the nitrocellulose-coated flow cells for 1 min, followed by 3 rinses with 0.5 mg/ml BSA in buffer B. Neutravidin (50 μg/ml; Thermo Scientific) in buffer B was applied for 1 min, followed by 3 rinses with buffer B. Before introduction into the flow cell, TgMyoA was mixed with a 2-fold molar excess of F-actin and 10 mM MgATP in buffer B and centrifuged for 25 min at 350,000×g to remove ATP-insensitive myosin heads. TgMyoA was then introduced into the flow cell at 70 μg/ml. To further block any ATP-insensitive heads, 1 μM vortexed Factin in buffer C (50 mM KCl, 25 mM imidazole, pH 7.5, 1 mM EGTA, 4 mM MgCl₂, 10 mM DTT) was added for 60 s, followed by a 10 mM MgATP wash. Rhodamine-phalloidin-labeled actin was then introduced for 1 min, followed by one rinse with buffer C. Three volumes of Buffer C, which also contained 5 mM MgATP (unless stated otherwise), 0.5%-0.7% methylcellulose, 25 μg/ml TgMLC1 and 25 μg/ml TgELC1, 3 mg/ml glucose, 0.125 mg/ml glucose oxidase (Sigma-Aldrich), and 0.05 mg/ml catalase (Sigma-Aldrich), were then flowed in. When assayed with calcium, 1.2 mM calcium was added to this buffer.

Actin movement was observed at 30° C. using an inverted microscope (Zeiss Axiovert 10) equipped with epi-fluorescence, a Rolera MGi Plus Digital camera, and dedicated computer with the Nikon NIS Elements software package. Data were analyzed using a semi-automated filament tracking program described in (10). The velocities of >600 filaments were determined. Speeds were fit to a Gaussian curve.

Actin-Activated ATPase Activity—

Assays were performed in 10 mM imidazole, pH 7.0, 5 mM NaCl, 1 mM MgCl₂, 1 mM NaN3, and 1 mM DTT at 30° C. Purified TgMyoA (7.5 μg/ml) was incubated with various concentrations of skeletal actin. Activity was initiated by the addition of 5 mM MgATP and stopped with SDS every 2 min for 8 min. Inorganic phosphate was determined colorimetrically (33). The low salt concentration was needed to keep the Km values as low as possible. Data were fit to the Michaelis-Menten equation.

Sedimentation Velocity—

Sedimentation velocity runs were performed at 20° C. in an Optima XL-I analytical ultracentrifuge (Beckman Coulter) using the An60Ti rotor at 30,000 rpm. The solvent was 20 mM HEPES, pH 7.4, 0.1 M NaCl, 2 mM DTT. An N-terminally FLAG-tagged TgMyoA heavy chain (no Bio tag) bound to TgMLC1 was used for this experiment. The sedimentation coefficient was determined by curve fitting to one species, using the dc/dt program (34).

Results

TgMyoA Heavy Chain is Insoluble when Expressed in Sf9 Cells—

Recombinant baculoviruses encoding TgMyoA heavy chain and its regulatory light chain, TgMLC1, were used to co-infect Sf9 cells. The C-terminus of the TgMyoA heavy chain contained two tags: a FLAG-tag to facilitate purification by affinity chromatography, and a Biotag, which becomes biotinylated within the Sf9 cells (35) and allows the motor to be specifically attached via its C-terminus to a streptavidin-coated coverslip for in vitro motility assays (FIG. 2A). Although both TgMyoA heavy chain and TgMLC1 were expressed following infection, as detected by Western blotting of the total Sf9 cell lysate, none of the TgMyoA heavy chain was present in the soluble fraction (FIG. 3).

Identification of a UCS Family Gene in the T. gondii Genome—

The studies suggested that the endogenous Sf9 protein folding machinery was not sufficient to fold this unusual myosin, and that a parasite-specific co-factor was required. A potential candidate was a protein in the UCS family of myosin co-chaperones, of which UNC-45 from C. elegans is the founding member. Bioinformatic analysis of the T. gondii genome using either full length Unc45 or the UCS domain revealed a candidate, TgUNC (http://toxodb.org/toxo/; TgGT1_249480). The TgUNC amino acid sequence was aligned with the three canonical members of the UCS family of myosin chaperones (C. elegans Unc45b, P. anserina CRO1, and S. cerevisiae She4p) (FIG. 10). The percent identity/percent similarity of full-length TgUNC with the other UCS family members was determined and was found to be: Unc45b, 17.4/28.7; CRO1, 9.5/16.3; She4p, 9.3/17.4. Comparing only the UCS domains, the percent identity/percent similarity with TgUNC increases to: Unc45b, 20.4/31.1; CRO1, 17.4/27.3; She4p, 15.3/25.3. A schematic of the domain structure of TgUNC is shown in FIG. 2B.

Production of Soluble TgMyoA in Sf9 Cells Requires Co-Expression with TgUNC—

In marked contrast to what was observed in the absence of TgUNC, co-expression of TgMyoA heavy chain and TgMLC1 with TgUNC yielded soluble protein in small-scale infections (FIG. 3). A large-scale infection for protein purification was set up (500 ml culture, 3×10⁹ Sf9 cells) using the same three viruses to co-infect Sf9 cells. TgMyoA was purified from the lysate using a FLAG-affinity column (see Methods above herein). Protein that bound to and eluted from the FLAG column showed two predominant bands on SDS-gels at the expected sizes of TgMyoA heavy chain and TgMLC1 (FIG. 4A, lane 1). The yield of purified motor was ˜1.5 mg/10⁹ Sf9 cells. The isolated expressed protein was analyzed by sedimentation velocity in the analytical ultracentrifuge. The results showed a single symmetrical peak with an S value of 7.75±0.01, indicating a homogeneous preparation of protein (FIG. 4B).

In Vitro Motility of Expressed TgMyoA Containing Bound TgMLC1—

Solubility does not ensure activity, so an in vitro motility assay was performed to assess function. TgMyoA with bound gMLC1 was perfused into a chamber containing a streptavidin-coated coverslip. The biotinylated tag at the C-terminus of TgMyoA heavy chain ensured that this region would adhere to the coverslip, leaving the motor domain accessible to bind actin. Expressed protein moved rhodamine-phalloidin labeled skeletal muscle actin at a speed of 1.5±0.2 μm/s (FIG. 5, solid triangles). Speeds were calculated using a semi-automated tracking program that allowed thousands of trajectories to be analyzed without selection bias (10). The speeds fit a Gaussian distribution.

The speed obtained with expressed protein was slower than the speed of protein isolated from parasites (8,12), which suggested a need to identify an additional component of the motor complex.

Co-Expression of TgMyoA Heavy Chain with Both TgMLC1 and TgELC1—

In addition to TgMLC1, an essential light chain called TgELC1 was recently identified as part of the myosin motor complex (6). When TgELC1 was co-expressed with TgMyoA heavy chain, TgMLC1, and TgUNC, both light chains were found to co-purify with the heavy chain, indicating that, like TgMLC1, TgELC1 is a tightly bound subunit of TgMyoA. When TgMyoA containing both light chains was assayed in the in vitro motility assay, it moved actin at 3.4±0.7 μm/s, more than twice the speed seen with TgMyoA containing only TgMLC1 (FIG. 5, solid circles).

Each TgMyoA Heavy Chain Binds Simultaneously to a Regulatory and Essential Light Chain—

To test whether TgMLC1 and TgELC1 bind simultaneously to the same heavy chain, a recombinant baculovirus was prepared that contained both light chains, each with a different tag. TgMLC1 had an N-terminal 3×Myc tag, while TgELC1 had a C-terminal 3×HA tag. 72 hours following infection with heavy and light chains, TgMyoA was immunoprecipitated from the Sf9 cell lysate with either an anti-HA antibody (TgELC1) or an anti-TgMLC1 antibody (FIG. 6). The Myc antibody could not be used for TgMLC1 immunoprecipitation because TgUNC was also tagged with Myc. The eluates from the immunoprecipitation were analyzed by Western blotting with antibodies to detect TgUNC (anti-Myc), TgMyoA heavy chain (anti-FLAG), TgMLC1 (anti-Myc), and TgELC1 (anti-HA). The results showed that the proteins co-immunoprecipitating with TgMLC1 included TgELC1, and conversely that the proteins co-immunoprecipitating with TgELC1 included TgMLC1. Earlier work showed that individual motor complexes do not physically associate with each other (12), and it was conclude that both light chains are simultaneously present on the TgMyoA heavy chain.

Calcium does not Regulate Motility Speed—

To determine if calcium affects the speed at which TgMyoA moves actin, an in vitro motility assay was performed in the presence or absence of free calcium. TgMyoA was pre-incubated in buffer containing either 0.2 mM free calcium or 1 mM EGTA for one hour before performing the assay. Whether the myosin contained TgMLC1 or both light chains, no difference in speed was observed in the presence or absence of calcium (FIG. 5, open symbols).

Steady State Actin-Activated ATPase Activity—

The speed of actin filament movement increased as the MgATP concentration in the in vitro motility assay increased (FIG. 7A). The fit to a rectangular hyperbola defined a Vmax of 4.6±0.3 μm/s and a Km of 1.3±0.3 mM MgATP. Based on this observation, steady-state actin-activated ATPase assays were performed with 5 mM MgATP. Rates of ATP hydrolysis were determined as a function of skeletal actin concentration. Data were fit to the Michaelis-Menten equation. TgMyoA expressed with both light chains showed a Vmax of 84±9.5 s⁻¹ and a Km for actin of 136±22 μM at 30° C. (FIG. 7B).

The TPR Domain of TgUNC is not Required to Express Functional Myosin—

Having established the properties of functional TgMyoA, studies were performed to determine the minimal domain of TgUNC that produced an active motor. In addition to full-length TgUNC, two shorter constructs were cloned (FIG. 2B), one of which (ΔTPR) contained the central and UCS domains, while the other (UCS) contained the UCS domain only. Small-scale baculovirus infections were performed using these three TgUNC constructs, and expression and solubility of TgMyoA were determined by Western blotting. Total (T) and soluble (S) fractions were probed with either anti-FLAG (top panel) for TgMyoA heavy chain or anti-Myc (bottom panel) for TgUNC and its truncations (FIG. 8). The results showed that the TPR domain was dispensable to obtain soluble myosin, while the UCS domain alone produced very little soluble myosin.

To determine the functionality of the TgMyoA, large-scale infections and purifications were done with each of the TgUNC constructs, co-expressed with TgMyoA heavy chain and both light chains. All three infections yielded protein, but the yields were reduced for the two shorter TgUNC constructs. Per 10⁹ Sf9 cells, full-length TgUNC yielded ˜1.5 mg TgMyoA, ΔTPR ˜0.35 mg TgMyoA, and UCS only ˜0.1 mg TgMyoA. In the in vitro motility assay, the motor expressed with either full-length TgUNC or ΔTPR generated similar actin sliding speeds (3.4±0.7 μm/s and 3.1±0.5 μm/s, respectively; see FIG. 9). In contrast, speeds decreased more than four-fold, to 0.7±0.2 μm/s, when TgMyoA was expressed in the presence of the UCS domain alone (FIG. 9).

DISCUSSION

It has now been shown that the class XIVa myosin motor TgMyoA simultaneously binds two light chains: the well-established TgMLC1 and a second light chain called TgELC1 (6,8). TgMyoA thus has a domain structure more similar to conventional myosins than previously appreciated. The results of the studies outlined above herein indicate that TgMyoA has a fairly conventional lever arm with two bound light chains, formed by TgELC1 and TgMLC1 binding to adjacent sites at the C terminus of the TgMyoA heavy chain. The lever arm functions to amplify small changes at the active site into the larger motions necessary to propel actin at fast speeds, and the length of the lever arm dictates the speed. TgMyoA with only TgMLC1 bound moved actin at half the speed of TgMyoA with both TgMLC1 and TgELC1 bound (1.5 μm/s vs. 3.4 μm/s). Consistent with the functional data, reciprocal co-immunoprecipitations showed that the TgMyoA heavy chain simultaneously bound both types of light chains, establishing that TgMLC1 and TgELC1 bind to non-overlapping sites on the heavy chain.

Role of TgMyoA Light Chains—

The results of the studies indicate that TgELC1 is a bona fide subunit of TgMyoA. The in vitro motility data show that TgMyoA moves actin at the same speed in the presence or absence of calcium, and does not support the idea that calcium binding directly regulates this motor. Increased levels of intracellular calcium within the parasite may instead trigger signaling pathways that lead to increased association of TgELC1 with TgMyoA.

Motor Activity—

The steady-state ATPase assay showed that TgMyoA has a low affinity (i.e., a high Km) for actin in the presence of MgATP, as expected for a single-headed motor. The extrapolated maximal ATPase rate of ˜80 sec-1 gives a total time per cycle of MgATP hydrolysis of ˜12 msec. From the measured unitary step-size (duni) of 5.3 nm (8) and a speed of actin movement of ˜3.4 μm/s (v), the time the motor spends strongly attached to actin is ˜1.5 msec (ton=duni/v). This is a small percentage of the total cycle time, and thus this motor has a low duty cycle, as do most motors designed for speed.

Proper Folding of TgMyoA Heavy Chain Requires a Parasite-Specific Myosin Co-Chaperone—

A main finding of the studies described herein was that a T. gondii myosin co-chaperone is required to properly fold TgMyoA heavy chain in the baculovirus/Sf9 insect cell expression system. This was the first demonstration that functional class XIV myosin from an apicomplexan parasite can be expressed in a heterologous system. While TgMyoA can be purified directly from the parasite, the yields are low, making it difficult to rigorously characterize the parasite-derived motor complex. With the heterologous expression system described herein, yields of 1 mg were readily attainable from 1×10⁹ infected Sf9 cells (200 ml culture), comparable to yields obtained with myosins that do not require coexpression with an exogenous chaperone. Importantly, the speed at which expressed TgMyoA with two bound light chains moves actin in an in vitro motility assay (˜3.4 μm/s) is close to the speed of the motor complex isolated from parasites (˜5 μm/s) (8,12). The difference in the two values may be simply due to differences in the way the speeds were calculated. In studies described herein, a tracking program was used that calculates speeds of hundreds of moving filaments without user-bias, while prior studies tracked individual filaments manually.

The TPR Domain of TgUNC is not Required for its Chaperone Activity—

TgUNC has all three domains found in the canonical Unc45 protein, i.e., an N-terminal TPR domain, a central domain, and a C-terminal UCS domain that binds to myosin (see FIG. 2B). It has now been shown that the N-terminal TPR domain of TgUNC is not necessary to obtain functional TgMyoA in Sf9 cells. Both the myosin-binding UCS domain and the central domain are, however, required.

The long-sought goal of obtaining milligram quantities of TgMyoA has now been reached, which for the first time makes high-throughput screening for drugs against this unusual, virulence-associated motor possible. Furthermore, the results of these studies supports a conclusion that genomes of other apicomplexan parasites encode homologs of TgUNC, and that the approach described herein may be used for the expression of functional class XIV myosins from other apicomplexan parasites of medical and/or veterinary importance.

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Although several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto; the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified, unless clearly indicated to the contrary.

All references, patents, patent applications, and non-patent publications that are cited or referred to in this application are incorporated in their entirety herein by reference. 

What is claimed is:
 1. A method of producing a functional class XIV myosin polypeptide, the method comprising, co-expressing three or more polynucleotides in a heterologous expression-system cell, wherein the three or more polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide, a first myosin light chain polypeptide-encoding polynucleotide, and a parasite co-chaperone polypeptide-encoding polynucleotide, wherein the three or more polynucleotides are co-expressed in the cell under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first myosin light chain polypeptide.
 2. The method of claim 1, wherein the class XIV heavy chain polypeptide-encoding polynucleotide, the parasite co-chaperone polypeptide-encoding polynucleotide, and the first myosin light chain polypeptide-encoding polynucleotide are each independently selected from a Toxoplasma, Plasmodium, Neospora, Sarcocystis, Eimeria, or Cryptosporidium class XIV heavy chain polypeptide-encoding polynucleotide; a parasite co-chaperone polypeptide-encoding polynucleotide; and a myosin light chain polypeptide-encoding polynucleotide, respectively; and wherein the encoded class XIV heavy chain polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type class XIV heavy chain polypeptide or a functional fragment thereof; the encoded first myosin light chain polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type myosin light chain polypeptide or a functional fragment thereof; and the encoded parasite co-chaperone polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type parasite co-chaperone polypeptide or a functional fragment thereof.
 3. The method of claim 1, wherein co-expressing comprises co-infecting the heterologous expression-system cell with one or more expression vectors each comprising one or more of the three or more polynucleotides.
 4. The method of claim 3, wherein the one or more expression vectors is a viral expression vector.
 5. The method of claim 3, wherein co-infecting the heterologous expression-system cell comprises co-infecting with one or more expression vectors comprising one or more of the class XIV heavy chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, the first myosin light chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, and the parasite co-chaperone polypeptide-encoding polynucleotide operably linked to an independently selected promoter.
 6. The method of claim 3, wherein co-infecting the heterologous expression-system cell comprises co-infecting with a first expression vector comprising the class XIV heavy chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, a second expression vector comprising the first myosin light chain polypeptide-encoding polynucleotide operably linked to an independently selected promoter, and a third expression vector comprising the parasite co-chaperone polypeptide-encoding polynucleotide operably linked to an independently selected promoter.
 7. The method of claim 3, wherein the one or more of the expression vectors additionally comprises one or more polynucleotides that encode: a myosin light chain-1 (MLC1) polypeptide having at least 75% similarity to the sequence of a wild-type MLC1 polypeptide or a functional fragment thereof; a tail domain interacting protein (MTIP) polypeptide having at least 75% similarity to the sequence of a wild-type MTIP polypeptide or a functional fragment thereof; an essential light chain-1 (ELC1) polypeptide having at least 75% similarity to the sequence of a wild-type ELC1 polypeptide or a functional fragment thereof; a calmodulin polypeptide having at least 75% similarity to the sequence of a wild-type calmodulin) polypeptide or a functional fragment thereof; or a glideosome associated protein-45 (GAP45) polypeptide having at least 75% similarity to the sequence of a wild-type GAP45 polypeptide or a functional fragment thereof.
 8. The method of claim 3, wherein one or more of the expression vectors additionally comprise at least one polynucleotide sequence that encodes a detectable label, and wherein the functional class XIV myosin polypeptide comprises the expressed detectable label polypeptide.
 9. The method of claim 1, wherein the parasite co-chaperone polypeptide-encoding polynucleotide sequence comprises a UNC-45/Cro1/She4p (UCS) chaperone polynucleotide sequence encoding a parasite co-chaperone polypeptide having at least 75% similarity to the sequence of a wild-type UNC-45/Cro1/She4p (UCS) polypeptide or a functional fragment thereof, respectively.
 10. The method of claim 1, wherein the encoded parasite co-chaperone polypeptide comprises an amino acid sequence having at least 75% similarity to the sequence of a wild-type toxoplasma gondii UCS-45 homolog or a functional fragment thereof; or a wild-type Toxoplasma UNC (TgUNC) polypeptide or a functional fragment thereof.
 11. The method of claim 1, wherein the parasite co-chaperone polypeptide comprises an amino acid sequence having at least 75% similarity to: the sequence of a wild-type Plasmodium falciparum UCS-45 homolog or a functional fragment thereof; or a wild-type Plasmodium falciparum UNC (PfUNC) polypeptide, or a functional fragment thereof.
 12. The method of claim 11, wherein the PfUNC functional fragment is a truncated PfUNC polypeptide.
 13. The method of claim 1, wherein the heterologous expression system is a baculovirus/insect cell expression system.
 14. The method of claim 1, wherein the first myosin light chain polypeptide is a regulatory light chain (MLC1) polypeptide comprising an amino acid sequence having at least 75% similarity to: a wild-type Toxoplasma gondii regulatory light chain polypeptide sequence or a functional fragment thereof; or a wild-type Plasmodium falciparum regulatory light chain polypeptide sequence or a functional fragment thereof.
 15. The method of claim 1, further comprising isolating the expressed functional class XIV myosin polypeptide.
 16. The method of claim 1, further comprising assaying the function of the expressed functional class XIV myosin polypeptide.
 17. The method of claim 1, further comprising co-infecting the heterologous expression-system cell with an expression vector comprising a second myosin light chain encoding polynucleotide; and co-expressing the class XIV heavy chain polynucleotide, the first and second myosin light chain polynucleotides, and the parasite co-chaperone polynucleotide under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first and second myosin light chain polypeptides.
 18. A functional class XIV myosin polypeptide prepared by the method of claim
 8. 19. A method of determining an activity of a class XIV myosin polypeptide, the method comprising, (a) preparing a functional class XIV myosin polypeptide with a method comprising co-expressing three or more polynucleotides in an expression-system cell, wherein the three or more polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide, a first myosin light chain polypeptide-encoding polynucleotide, and a parasite co-chaperone polypeptide-encoding polynucleotide, wherein the three or more polynucleotides are co-expressed in the cell under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first myosin light chain polypeptide; (b) assaying an activity of the prepared functional class XIV myosin polypeptide; and (c) assessing the results of the assay as a determination of activity in the functional class XIV myosin polypeptide.
 20. A method of identifying a candidate compound to inhibit a parasite that expresses a class XIV myosin polypeptide, the method comprising, (a) preparing a functional class XIV myosin polypeptide with a method comprising, co-expressing three or more polynucleotides in an expression-system cell, wherein the three or more polynucleotides comprise a class XIV heavy chain polypeptide-encoding polynucleotide, a first myosin light chain polypeptide-encoding polynucleotide, and a parasite co-chaperone polypeptide-encoding polynucleotide, wherein the three or more polynucleotides are co-expressed in the cell under conditions suitable to produce a functional class XIV myosin polypeptide comprising the class XIV heavy chain polypeptide and the first myosin light chain polypeptide; (b) contacting the functional prepared class XIV myosin polypeptide with a candidate compound under conditions suitable to determine an activity of the class XIV myosin polypeptide; (c) determining the activity of the functional class XIV myosin polypeptide; and (d) comparing the determined activity with a control activity determination, wherein a decrease in the determined activity in the contacted functional class XIV myosin polypeptide compared to the control activity determination identifies the compound as a candidate compound to inhibit a parasite that expresses the functional class XIV myosin polypeptide.
 21. The method of claim 1, wherein the encoded class XIV heavy chain polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type class XIV heavy chain polypeptide or a functional fragment thereof; the encoded first myosin light chain polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type myosin light chain polypeptide or a functional fragment thereof; and the encoded parasite co-chaperone polypeptide comprises an amino acid sequence having at least 75% sequence similarity to a wild-type parasite co-chaperone polypeptide or a functional fragment thereof. 